Aromatization Processes Using Both Fresh and Regenerated Catalysts, and Related Multi-Reactor Systems

ABSTRACT

Multi-reactor systems with aromatization reactor vessels containing a catalyst with low surface area and pore volume, followed in series by aromatization reactor vessels containing a catalyst with high surface area and pore volume, are disclosed. Related reforming methods using the different aromatization catalysts also are described.

FIELD OF THE INVENTION

The present disclosure concerns catalytic reforming methods and relatedaromatization reactor vessels, and more particularly relates to the useof a fresh aromatization catalyst and a regenerated aromatizationcatalyst in different reactor vessels within a multi-reactor system.

BACKGROUND OF THE INVENTION

The catalytic conversion of non-aromatic hydrocarbons into aromaticcompounds, often referred to as aromatization or reforming, is animportant industrial process that can be used to produce benzene,toluene, xylenes, and the like. The aromatization or reforming processoften is conducted in a reactor system that can contain two or morereactors containing transition metal based catalysts. These catalystscan provide increased selectivity to the desired aromatic compounds.However, under commercial reaction conditions, these catalysts slowlylose their activity, often simultaneously with a loss of selectivity tothe desired aromatic compounds. Such catalysts are often referred to as“spent” catalysts once economic or operational thresholds are passed,and such spent catalysts can be “regenerated” using various proceduresand techniques.

Due to the raw material cost of fresh catalyst, it would be beneficialto use regenerated catalyst in combination with fresh catalyst inaromatization reactor systems and related aromatization processes.Accordingly, it is to these ends that the present disclosure isgenerally directed.

SUMMARY OF THE INVENTION

Various aromatization processes are disclosed and described herein. Onesuch aromatization process can comprise (i) introducing a firsthydrocarbon feed into at least one first reactor vessel comprising afirst aromatization catalyst, and contacting the first hydrocarbon feedwith the first aromatization catalyst under first reforming conditionsto produce a first aromatic product; wherein the first aromatizationcatalyst (e.g., a regenerated aromatization catalyst) comprises a firsttransition metal and a first catalyst support, the first aromatizationcatalyst characterized by a first surface area in a range from about 80m²/g to about 150 m²/g, and/or a first micropore volume in a range fromabout 0.01 cc/g to about 0.048 cc/g; (ii) discharging a first effluentcomprising the first aromatic product from the at least one firstreactor vessel; (iii) heating the first effluent to form a secondhydrocarbon feed; (iv) introducing the second hydrocarbon feed into atleast one second reactor vessel comprising a second aromatizationcatalyst, and contacting the second hydrocarbon feed with the secondaromatization catalyst under second reforming conditions to produce asecond aromatic product; wherein the second aromatization catalyst(e.g., a fresh aromatization catalyst) comprises a second transitionmetal and a second catalyst support, the second aromatization catalystcharacterized by a second surface area in a range from about 160 m²/g toabout 260 m²/g, and/or a second micropore volume in a range from about0.05 cc/g to about 0.09 cc/g; and (v) discharging a second effluentcomprising the second aromatic product from the at least one secondreactor vessel.

Also disclosed herein are aromatization reactor vessel systems. Forexample, an illustrative aromatization reactor vessel system cancomprise (A) at least one first reactor vessel comprising (a1) a firstreactor inlet for introducing a first hydrocarbon feed into the at leastone first reactor vessel; (a2) a first aromatization catalyst forcatalytically converting at least a portion of the first hydrocarbonfeed under first reforming conditions to produce a first aromaticproduct; wherein the first aromatization catalyst (e.g., a regeneratedaromatization catalyst) comprises a first transition metal and a firstcatalyst support; the first aromatization catalyst characterized by afirst surface area in a range from about 80 m²/g to about 150 m²/g,and/or a first micropore volume in a range from about 0.01 cc/g to about0.048 cc/g; and (a3) a first reactor outlet for discharging a firsteffluent comprising the first aromatic product from the at least onefirst reactor vessel; (B) at least one second reactor vessel comprising(b1) a second reactor inlet for introducing a second hydrocarbon feedinto the at least one second reactor vessel; (b2) a second aromatizationcatalyst for catalytically converting at least a portion of the secondhydrocarbon feed under second reforming conditions to produce a secondaromatic product; wherein the second aromatization catalyst (e.g., afresh aromatization catalyst) comprises a second transition metal and asecond catalyst support, the second aromatization catalyst characterizedby a second surface area in a range from about 160 m²/g to about 260m²/g, and/or a second micropore volume in a range from about 0.05 cc/gto about 0.09 cc/g; and (b3) a second reactor outlet for discharging asecond effluent comprising the second aromatic product from the at leastone second reactor vessel; and (C) a furnace positioned between thefirst reactor outlet and the second reactor inlet, the furnace capableof heating the first effluent to form the second hydrocarbon feed.

In these and other aspects of the invention, the at least one firstreactor vessel can comprise one first reactor vessel or a series of twoor more first reactor vessels. Likewise, the at least one second reactorvessel can comprise one second reactor vessel or a series of two or moresecond reactor vessels.

Both the foregoing summary and the following detailed descriptionprovide examples and are explanatory only. Accordingly, the foregoingsummary and the following detailed description should not be consideredto be restrictive. Further, features or variations can be provided inaddition to those set forth herein. For example, certain aspects can bedirected to various feature combinations and sub-combinations describedin the detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this disclosure, illustrate various aspects of the presentinvention. In the drawings:

FIG. 1 illustrates a reactor system containing two reactor vessels and afurnace, in an aspect of the present invention.

FIG. 2 illustrates a reactor system containing a series of furnaces andreactor vessels, in another aspect of the present invention.

FIG. 3 presents a plot of the aromatics selectivity versus reaction timefor the fresh catalyst of Example 1 and the regenerated catalyst ofExample 2.

FIG. 4 presents a plot of the yield adjusted catalyst temperature versusreaction time for the fresh catalyst of Example 1 and the regeneratedcatalyst of Example 2.

FIG. 5 presents a plot of the yield adjusted catalyst temperature versusreaction time for the fresh catalyst of Example 3 and the regeneratedcatalyst of Example 4.

FIG. 6 presents a plot of the aromatics selectivity versus reaction timefor the fresh catalyst of Example 3 and the regenerated catalyst ofExample 4.

FIG. 7 presents a plot of the yield adjusted catalyst temperature versusreaction time for the fresh catalyst of Example 3 and the regeneratedcatalyst of Example 5.

FIG. 8 presents a plot of the aromatics selectivity versus reaction timefor the fresh catalyst of Example 3 and the regenerated catalyst ofExample 5.

FIG. 9 presents a plot of the yield adjusted catalyst temperature versusreaction time for the spent catalyst, the fresh catalyst of Example 6,and the regenerated catalyst of Example 7.

FIG. 10 presents a plot of the benzene+toluene selectivity versusreaction time for the spent catalyst, the fresh catalyst of Example 6,and the regenerated catalyst of Example 7.

DEFINITIONS

To define more clearly the terms used herein, the following definitionsare provided. Unless otherwise indicated, the following definitions areapplicable to this disclosure. If a term is used in this disclosure butis not specifically defined herein, the definition from the IUPACCompendium of Chemical Terminology, 2^(nd Ed ()1997), can be applied, aslong as that definition does not conflict with any other disclosure ordefinition applied herein, or render indefinite or non-enabled any claimto which that definition is applied. To the extent that any definitionor usage provided by any document incorporated herein by referenceconflicts with the definition or usage provided herein, the definitionor usage provided herein controls.

Herein, features of the subject matter are described such that, withinparticular aspects, a combination of different features can beenvisioned. For each and every aspect and each and every featuredisclosed herein, all combinations that do not detrimentally affect thedesigns, compositions, processes, or methods described herein arecontemplated with or without explicit description of the particularcombination. Additionally, unless explicitly recited otherwise, anyaspect or feature disclosed herein can be combined to describe inventivedesigns, compositions, processes, or methods consistent with the presentdisclosure.

While apparatuses, systems, and methods/processes are described hereinin terms of “comprising” various components, devices, or steps, theapparatuses, systems, and methods/processes can also “consistessentially of” or “consist of” the various components, devices, orsteps, unless stated otherwise.

The terms “a,” “an,” and “the” are intended to include pluralalternatives, e.g., at least one. For instance, the disclosure of “atransition metal” or “a furnace,” is meant to encompass one, or mixturesor combinations of more than one, transition metal or furnace, unlessotherwise specified.

A “spent” catalyst is used herein generally to describe a catalyst thathas unacceptable performance in one or more of catalyst activity,selectivity to a desired product(s), or an operating parameter, such asmaximum operating temperature or pressure drop across a reactor,although the determination that a catalyst is “spent” is not limitedonly to these features. The unacceptable performance of the spentcatalyst can be due to a sulfur or carbonaceous build-up on the catalystover time, but is not limited thereto. In some aspects, the “fresh”catalyst can have an activity X, the “spent” catalyst can have anactivity Z, and a “regenerated” catalyst can have an activity Y, suchthat Z<Y≤X. In certain aspects disclosed herein, the regeneratedcatalyst can have substantially the same catalyst activity as that ofthe fresh catalyst. Such catalyst activity comparisons (and otherreforming performance characteristics, such as selectivity) are meant touse the same production run (batch) of catalyst, tested on the sameequipment, and under the same test method and conditions. The“regenerated” catalyst encompasses catalysts that are regenerated usingany suitable combination of catalyst regeneration steps, and optionally,this can include a reduction step (e.g., using hydrogen).

The amounts of any components or materials present on the catalystsdescribed herein are on a weight basis, such as wt. % or ppmw (ppm byweight), unless otherwise specified. These components or materials caninclude, for instance, the amount of carbon, the amount of fluorine, theamount of chlorine, the amount of platinum, and so forth.

Generally, groups of elements are indicated using the numbering schemeindicated in the version of the periodic table of elements published inChemical and Engineering News, 63(5), 27, 1985. In some instances, agroup of elements can be indicated using a common name assigned to thegroup; for example, alkali metals for Group 1 elements, alkaline earthmetals for Group 2 elements, transition metals for Group 3-12 elements,noble metals for Group 8-10 elements, and halogens or halides for Group17 elements.

For any particular compound or group disclosed herein, any name orstructure (general or specific) presented is intended to encompass allconformational isomers, regioisomers, stereoisomers, and mixturesthereof that can arise from a particular set of substituents, unlessotherwise specified. The name or structure (general or specific) alsoencompasses all enantiomers, diastereomers, and other optical isomers(if there are any) whether in enantiomeric or racemic forms, as well asmixtures of stereoisomers, as would be recognized by a skilled artisan,unless otherwise specified. For example, a general reference to hexaneincludes n-hexane, 2-methyl-pentane, 3-methyl-pentane,2,2-dimethyl-butane, and 2,3-dimethyl-butane; and a general reference toa butyl group includes a n-butyl group, a sec-butyl group, an iso-butylgroup, and a t-butyl group.

In one aspect, a chemical “group” can be defined or described accordingto how that group is formally derived from a reference or “parent”compound, for example, by the number of hydrogen atoms removed from theparent compound to generate the group, even if that group is notliterally synthesized in such a manner. These groups can be utilized assubstituents or coordinated or bonded to metal atoms. By way of example,an “alkyl group” formally can be derived by removing one hydrogen atomfrom an alkane. The disclosure that a substituent, ligand, or otherchemical moiety can constitute a particular “group” implies that thewell-known rules of chemical structure and bonding are followed whenthat group is employed as described. When describing a group as being“derived by,” “derived from,” “formed by,” or “formed from,” such termsare used in a formal sense and are not intended to reflect any specificsynthetic methods or procedures, unless specified otherwise or thecontext requires otherwise.

Various numerical ranges are disclosed herein. When a range of any typeis disclosed or claimed, the intent is to disclose or claim individuallyeach possible number that such a range could reasonably encompass,including end points of the range as well as any sub-ranges andcombinations of sub-ranges encompassed therein, unless otherwisespecified. As a representative example, the present applicationdiscloses that the methods provided herein can employ a catalystcontaining F and Cl at a molar ratio of F:Cl in a range from about 0.5:1to about 4:1 in certain aspects. By a disclosure that the molar ratio ofF:Cl can be in a range from about 0.5:1 to about 4:1, the intent is torecite that the molar ratio can be any molar ratio within the range and,for example, can be equal to about 0.5:1, about 0.6:1, about 0.7:1,about 0.8:1, about 0.9:1, about 1:1, about 2:1, about 3:1, or about 4:1.Additionally, the molar ratio of F:Cl can be within any range from about0.5:1 to about 4:1 (for example, the molar ratio can be in a range fromabout 0.5:1 to about 2:1), and this also includes any combination ofranges between about 0.5:1 and about 4:1. Likewise, all other rangesdisclosed herein should be interpreted in a manner similar to thisexample.

The term “about” means that amounts, sizes, formulations, parameters,and other quantities and characteristics are not and need not be exact,but can be approximate including being larger or smaller, as desired,reflecting tolerances, conversion factors, rounding off, measurementerrors, and the like, and other factors known to those of skill in theart. In general, an amount, size, formulation, parameter or otherquantity or characteristic is “about” or “approximate” whether or notexpressly stated to be such. The term “about” also encompasses amountsthat differ due to different equilibrium conditions for a compositionresulting from a particular initial mixture. Whether or not modified bythe term “about,” the claims include equivalents to the quantities. Theterm “about” can mean within 10% of the reported numerical value,preferably within 5% of the reported numerical value.

The term “substituted” when used to describe a group, for example, whenreferring to a substituted analog of a particular group, is intended todescribe any non-hydrogen moiety that formally replaces a hydrogen atomin that group, and is intended to be non-limiting. A group or groups canalso be referred to herein as “unsubstituted” or by equivalent termssuch as “non-substituted,” which refers to the original group in which anon-hydrogen moiety does not replace a hydrogen atom within that group.Unless otherwise specified, “substituted” is intended to be non-limitingand include inorganic substituents or organic substituents as understoodby one of ordinary skill in the art.

As used herein, the terms “hydrocarbon” or “hydrocarbon feed” refer tocompounds containing only carbon and hydrogen atoms. Other identifierscan be utilized to indicate the presence of particular groups, if any,in the hydrocarbon (e.g., halogenated hydrocarbon indicates that thepresence of one or more halogen atoms replacing an equivalent number ofhydrogen atoms in the hydrocarbon). The hydrocarbon or hydrocarbon feedmay be a naphtha stream or light naphtha stream. In certain aspects, thehydrocarbon feed may comprise C₆-C₈ alkanes and/or cycloalkanes (e.g.,hexane, heptane, cyclohexane, and methylcyclohexane, among others). Inthe cases where the catalyst may be a sulfur-sensitive catalyst, such asa large-pore zeolite catalyst comprising at least one alkali or alkalineearth metal and at least one Group VIII metal, the hydrocarbon orhydrocarbon feed may be a low-sulfur hydrocarbon or a low-sulfur naphthastream and may contain less than about 100 parts per billion by weight(ppb) sulfur; alternatively, less than about 50 ppb sulfur; oralternatively, less than about 25 ppb sulfur.

An “aromatic” compound is a compound containing a cyclically conjugateddouble bond system that follows the Htickel (4n+2) rule and contains(4n+2) pi-electrons, where n is an integer from 1 to 5. Aromaticcompounds include “arenes” (aromatic hydrocarbon compounds, e.g.,benzene, toluene, and xylenes) and “heteroarenes” (heteroaromaticcompounds formally derived from arenes by replacement of one or moremethine (−C═) carbon atoms of the cyclically conjugated double bondsystem with a trivalent or divalent heteroatoms, in such a way as tomaintain the continuous pi-electron system characteristic of an aromaticsystem and a number of out-of-plane pi-electrons corresponding to theHtickel rule (4n+2)). As disclosed herein, the term “substituted” can beused to describe an aromatic group, arene, or heteroarene, wherein anon-hydrogen moiety formally replaces a hydrogen atom in the compound,and is intended to be non-limiting, unless specified otherwise.

As used herein, the term “alkane” refers to a saturated hydrocarboncompound. Other identifiers can be utilized to indicate the presence ofparticular groups, if any, in the alkane (e.g., halogenated alkaneindicates that the presence of one or more halogen atoms replacing anequivalent number of hydrogen atoms in the alkane). The term “alkylgroup” is used herein in accordance with the definition specified byIUPAC: a univalent group formed by removing a hydrogen atom from analkane. The alkane or alkyl group can be linear or branched unlessotherwise specified.

A “cycloalkane” is a saturated cyclic hydrocarbon, with or without sidechains, for example, cyclobutane, cyclopentane, cyclohexane, methylcyclopentane, and methyl cyclohexane. Other identifiers can be utilizedto indicate the presence of particular groups, if any, in thecycloalkane (e.g., halogenated cycloalkane indicates that the presenceof one or more halogen atoms replacing an equivalent number of hydrogenatoms in the cycloalkane).

The term “halogen” has its usual meaning. Examples of halogens includefluorine, chlorine, bromine, and iodine.

The term “contacting” is used herein to describe methods, processes, andcompositions wherein the components are contacted or combined togetherin any order, in any manner, and for any length of time, unlessotherwise specified. For example, the components can be contacted byblending or mixing. Further, unless otherwise specified, the contactingof any component can occur in the presence or absence of any othercomponent of the methods, processes, and compositions described herein.Combining additional materials or components can be done by any suitabletechnique. Further, “contacting” two or more components can result in asolution, a slurry, a mixture, a reaction mixture, or a reactionproduct.

Molar selectivities to a desired product are defined as:

$\begin{matrix}\begin{matrix}{{Benzene}\mspace{14mu} {selectivity}\text{:}} \\{S_{Bz} = \frac{{\overset{.}{n}}_{{Bz},{prod}}}{{\overset{.}{n}}_{{{convC}\; 6},{feed}} - {\overset{.}{n}}_{{{conv}\mspace{11mu} C\; 6},{prod}}}}\end{matrix} & \mspace{104mu} & {{Eq}.\mspace{14mu} 1} \\\begin{matrix}{{Toluene}\mspace{14mu} {selectivity}\text{:}} \\{S_{Tol} = \frac{{\overset{.}{n}}_{{Tol},{prod}}}{{\overset{.}{n}}_{{{convC}\; 7},{feed}} - {\overset{.}{n}}_{{{conv}\mspace{11mu} C\; 7},{prod}}}}\end{matrix} & \mspace{104mu} & {{Eq}.\mspace{14mu} 2} \\\begin{matrix}{{Benzene} + {{Toluene}\mspace{14mu} {selectivity}\text{:}}} \\{{S_{Bz} +_{Tol}} = \frac{{\overset{.}{n}}_{{Bz},{prod}} + {\overset{.}{n}}_{{Tol},{prod}}}{{\overset{.}{n}}_{{{convC}\; 6},{C\; 7},{feed}} - {\overset{.}{n}}_{{{conv}\mspace{11mu} C\; 6},{C\; 7},{prod}}}}\end{matrix} & \mspace{59mu} & {{Eq}.\mspace{14mu} 3} \\\begin{matrix}{{Aromatics}\mspace{14mu} {selectivity}\text{:}} \\{{S_{arom} = \frac{{\overset{.}{n}}_{{Bz},{prod}} + {\overset{.}{n}}_{{Tol},{prod}} + {\overset{.}{n}}_{{{C\; 8} + {arom}},{prod}}}{{\overset{.}{n}}_{{{{convC}\; 6} - {C\; 8} +},{feed}} - {\overset{.}{n}}_{{{{conv}\mspace{11mu} C\; 6} - {C\; 8} +},{prod}}}}\;}\end{matrix} & \mspace{50mu} & {{Eq}.\mspace{14mu} 4}\end{matrix}$

Conversion is defined as the number of moles converted per mol of“convertible” hydrocarbons fed:

$\begin{matrix}\begin{matrix}{C\; 6\mspace{14mu} {conversion}\text{:}} \\{X_{C\; 6} = \frac{{\overset{.}{n}}_{{{conv}\; C\; 6},{feed}} - {\overset{.}{n}}_{{{conv}\; C\; 6},{prod}}}{{\overset{.}{n}}_{{{convC}\; 6},{feed}}}}\end{matrix} & {{Eq}.\mspace{14mu} 5} & \; \\\begin{matrix}{C\; 7\mspace{14mu} {conversion}\text{:}} \\{X_{C\; 7} = \frac{{\overset{.}{n}}_{{{conv}\; C\; 7},{feed}} - {\overset{.}{n}}_{{{conv}\; C\; 7},{prod}}}{{\overset{.}{n}}_{{{convC}\; 7},{feed}}}}\end{matrix} & {{Eq}.\mspace{14mu} 6} & \; \\\begin{matrix}{{C\; 6} + {C\; 7\mspace{14mu} {conversion}\text{:}}} \\{X_{{C\; 6} + {C\; 7}} = \frac{{\overset{.}{n}}_{{{conv}\; C\; 6},\; {feed}} + {\overset{.}{n}}_{{{conv}\; C\; 7},{feed}} - {\overset{.}{n}}_{{{conv}\; C\; 6},{prod}} - {\overset{.}{n}}_{{{conv}\; C\; 7},{prod}}}{{\overset{.}{n}}_{{{conv}\; C\; 6},{feed}} + {\overset{.}{n}}_{{{conv}\; C\; 7},{feed}}}}\end{matrix} & {{Eq}.\mspace{14mu} 7} & \;\end{matrix}$

In these equations, n indicates a molar flow rate in a continuousreactor or the number of moles in a batch reactor.

As used herein, the term “convertible hydrocarbon,” “convertible C₆species,” or “convertible C₇ species” refers to a hydrocarbon compoundthat is readily reacted to form aromatic hydrocarbons underaromatization process conditions. A “non-convertible hydrocarbon” is ahighly-branched hydrocarbon that is not readily reacted to form aromatichydrocarbons under aromatization process conditions. A “non-convertiblehydrocarbon” can comprise highly-branched hydrocarbons having six orseven carbon atoms with an internal quaternary carbon, or hydrocarbonshaving six carbons atoms and two adjacent internal tertiary carbons, ormixtures thereof A “convertible C₆ species” is a hydrocarbon containingsix carbons without an internal quaternary carbon or two adjacentinternal tertiary carbons, for example, n-hexane, 2-methyl-pentane,3-methyl-pentane, cyclohexane, and methyl cyclopentane. A “convertibleC₇ species” is a hydrocarbon containing seven carbons without aninternal quaternary carbon, for example, n-heptane, 2-methyl-hexane,3-methyl-hexane, 2,3-dimethyl-pentane, 2,4-dimethyl-pentane, methylcyclohexane, and dimethyl cyclopentane. The highly branched hydrocarbonswith six or seven carbon atoms and an internal quaternary carbon cancomprise, for example, 2,2-dimethylbutane, 2,2-dimethylpentane,3,3-dimethylpentane, and 2,2,3-trimethylbutane. The highly branchedhydrocarbons with six carbon atoms and an adjacent internal tertiarycarbon can comprise, for example, 2,3-dimethylbutane. Thenon-convertible highly branched hydrocarbons do not easily convert toaromatic products, and instead tend to convert to light hydrocarbonsunder aromatization process conditions.

Although any methods and materials similar or equivalent to thosedescribed herein can be used in the practice or testing of theinvention, the typical methods and materials are herein described.

All publications and patents mentioned herein are incorporated herein byreference for the purpose of describing and disclosing, for example, theconstructs and methodologies that are described in the publications,which might be used in connection with the presently describedinvention.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description refers to the accompanying drawings.Wherever possible, the same or similar reference numbers are used in thedrawings and the following description to refer to the same or similarelements or features. While various aspects of the invention aredescribed, modifications, adaptations, and other implementations arepossible. For example, substitutions, additions, or modifications can bemade to the elements illustrated in the drawings, and the methodsdescribed herein can be modified by substituting, reordering, or addingstages to the disclosed methods. Accordingly, the following detaileddescription and its exemplary aspects do not limit the scope of theinvention.

Beneficially, the aromatization reactor vessel systems and processesdisclosed herein can employ a first aromatization catalyst that haslower surface area, lower pore volume, and lower platinum dispersionthan the second aromatization catalyst. Further, the first aromatizationcatalyst also can contain higher levels of iron, sulfur, and carbon thanthe second aromatization catalyst. Yet, despite these perceived negativecatalyst attributes, and unexpectedly, it was found that the firstaromatization catalyst (which can be a regenerated catalyst) often hascatalyst selectivity that is equivalent or even superior to that of thesecond aromatization catalyst (which can be a fresh catalyst).Typically, the first aromatization catalyst (e.g., a regeneratedcatalyst) has lower catalyst activity than the second aromatizationcatalyst (e.g., a fresh catalyst).

Thus, aromatization reactor vessel systems and processes can be designedas described herein, in which regenerated catalysts can be used, insteadof fresh catalysts (and the associated raw material costs), in the earlystages of aromatization systems and processes to convert the relativelymore easily convertible hydrocarbons (e.g., cyclohexane) with excellentselectivity, and where the lower catalyst activity is not detrimental tothe overall system and process.

Aromatization Reactor Vessel Systems

Generally, aromatization reactor vessel systems consistent with thepresent invention can comprise (A) at least one first reactor vesselcomprising (a1) a first reactor inlet for introducing a firsthydrocarbon feed into the at least one first reactor vessel; (a2) afirst aromatization catalyst for catalytically converting at least aportion of the first hydrocarbon feed under first reforming conditionsto produce a first aromatic product; wherein the first aromatizationcatalyst (e.g., a regenerated aromatization catalyst) comprises a firsttransition metal and a first catalyst support; the first aromatizationcatalyst characterized by a first surface area in a range from about 80m²/g to about 150 m²/g, and/or a first micropore volume in a range fromabout 0.01 cc/g to about 0.048 cc/g; and (a3) a first reactor outlet fordischarging a first effluent comprising the first aromatic product fromthe at least one first reactor vessel; (B) at least one second reactorvessel comprising (b1) a second reactor inlet for introducing a secondhydrocarbon feed into the at least one second reactor vessel; (b2) asecond aromatization catalyst for catalytically converting at least aportion of the second hydrocarbon feed under second reforming conditionsto produce a second aromatic product; wherein the second aromatizationcatalyst (e.g., a fresh aromatization catalyst) comprises a secondtransition metal and a second catalyst support, the second aromatizationcatalyst characterized by a second surface area in a range from about160 m²/g to about 260 m²/g, and/or a second micropore volume in a rangefrom about 0.05 cc/g to about 0.09 cc/g; and (b3) a second reactoroutlet for discharging a second effluent comprising the second aromaticproduct from the at least one second reactor vessel; and (C) a furnacepositioned between the first reactor outlet and the second reactorinlet, the furnace capable of heating the first effluent to form thesecond hydrocarbon feed.

FIG. 1 illustrates an aromatization reactor vessel system 100 consistentwith the present invention. While not being limited thereto, thearomatization reactor vessel system 100 is described herein as itpertains to its use in the catalytic conversion of a non-aromatichydrocarbon to produce an aromatic hydrocarbon, examples of whichinclude benzene, toluene, or xylenes, as well as mixtures thereof Thearomatization reactor vessel system 100 in FIG. 1 contains a firstreactor vessel 110, a second reactor vessel 130, and a furnace 120positioned between the reactor vessels. The first reactor vessel 110includes a first reactor inlet 105 for introducing a first hydrocarbonfeed into the first reactor vessel 110, a first reactor outlet 115 fordischarging a first effluent that contains a first aromatic product, anda first aromatization catalyst 112, positioned in the first reactorvessel 110, for catalytically converting at least a portion of the firsthydrocarbon feed to produce the first aromatic product.

Likewise, the second reactor vessel 130 includes a second reactor inlet125 for introducing a second hydrocarbon feed into the second reactorvessel 130, a second reactor outlet 135 for discharging a secondeffluent that contains a second aromatic product, and a secondaromatization catalyst 132, positioned in the second reactor vessel 130,for catalytically converting at least a portion of the secondhydrocarbon feed to produce the second aromatic product. As describedherein, both the first reactor vessel 110 and the second reactor vessel130 generally are configured for a catalytic conversion of non-aromatichydrocarbons to aromatic hydrocarbons, such as benzene and toluene.

The furnace 120 is positioned between the reactor vessels as shown inFIG. 1, specifically, between the first reactor outlet 115 and thesecond reactor inlet 125. The furnace 120 in FIG. 1 is capable ofheating the first effluent (in the first reactor outlet 115 from thefirst reactor vessel 110) to form the second hydrocarbon feed (in thesecond reactor inlet 125 to the second reactor vessel 130). Generally,the furnace 120 is configured to heat the first effluent to a reformingtemperature that is employed in the second reactor vessel 130, oftenranging from about 350° C. to about 600° C. While not shown in FIG. 1, afurnace can precede the first reactor vessel 110, and can heat the firsthydrocarbon feed in the first reactor inlet 105 to the desired reformingtemperature of the first reactor vessel 110, also often in a range fromabout 350° C. to about 600° C.

The first reactor vessel 110, the furnace 120, and the second reactorvessel 130 can be constructed of any suitable metal material, theselection of which can depend upon the desired operating temperature,desired operating pressure, and inertness to the reactor contents (forexample, catalyst, H₂, aromatic hydrocarbons, non-aromatichydrocarbons), amongst other factors. Typical metal materials includeaustenitic stainless steels, including 304, 316, 321, 347, 410S, 600, or800 stainless steel, and the like. Moreover, a protective coating orlayer containing any suitable material, compound, alloy, or metal, suchas tin, can used on any surface in the first reactor vessel 110, thefurnace 120, and/or the second reactor vessel 130 to provide resistanceto carburization and metal dusting. The metal protective layer maycomprise a nickel-depleted bonding layer disposed between the metalmaterials and the metal protective layer, wherein the metal protectivelayer is formed by applying a layer of at least one metal to the metalmaterials to form an applied metal layer on the substrate and curing theapplied metal layer form the metal protective layer on the substrate.The metal protective layer optionally may be further processed bymobilization and sequestration processes. The applied metal layer maycomprise tin oxide, a decomposable tin compound, and tin metal powder.The applied metal layer may be cured at a temperature of from about1,220° F. (660° C.) to about 1,400° F. (760° C.) and/or at a pressure offrom about 315 psia (2,172 kPa) to about 1 psia (0.05 Pa). The bondinglayer may comprise stannide and may have a thickness of about 1 to about100 μm. The bonding layer may comprise from about 1 wt. % to about 20wt. % elemental tin. The coated metal materials may be an any metalmaterials that contact a low-sulfur hydrocarbon. Representativeprotective layer materials are disclosed in U.S. Pat. Nos. 5,866,743,6,548,030, 8,119,203, and 9,085,736, which are incorporated herein byreference in their entirety.

Independently, the first reactor vessel 110 and the second reactorvessel 130 can be configured for reforming temperatures that typicallyfall within the 350° C. to 600° C. range, such as, for example, fromabout 400° C. to about 600° C., or from about 425° C. to about 575° C.In one aspect, the first reactor vessel 110 can be configured fordecreasing temperature from the first reactor inlet 105 to the firstreactor outlet 115. Additionally or alternatively, the second reactorvessel 130 can be configured for decreasing temperature from the secondreactor inlet 125 to the second reactor outlet 135. In these and otheraspects, the first reactor vessel 110 and the second reactor vessel 130can be configured for radial flow (i.e., the reactor vessels are radialflow reactors). However, the reactor vessels are not limited thereto.For instance, a traditional packed bed (or fixed bed) reactor can beemployed as the first reactor vessel 110 and/or the second reactorvessel 130, in aspects of this invention.

Likewise, the first reactor vessel 110 and the second reactor vessel 130can be configured, independently, for any suitable operating pressure,which can often be at least 20 psig (139 kPag), at least 25 psig (172kPag), or at least 30 psig (207 kPag), and in some aspects, up to anoperating pressure of as much as about 60 psig (414 kPag) to about 100psig (689 kPag). Hence, typical operating pressures include from about20 psig (139 kPag) to about 100 psig (689 kPag), or from about 25 psig(172 kPag) to about 60 psig (414 kPag). In some aspects, the reformingpressure in the first reactor vessel 110 can be greater than thereforming pressure in the second reactor vessel 130.

Additional information on features and designs of aromatization reactorvessels that can be employed in the aromatization reactor vessel systemsdescribed herein is disclosed in U.S. Pat. Nos. 6,548,030, 7,544,335,7,582,272, 8,119,203, and 9,085,736, which are incorporated herein byreference in their entirety.

The first reactor vessel 110 contains the first aromatization catalyst112. The first aromatization catalyst 112 can comprise a firsttransition metal and a first catalyst support, and can be characterizedby a first surface area in a range from about 80 m²/g to about 150 m²/g,and a first micropore volume in a range from about 0.01 cc/g to about0.048 cc/g. In some aspects, the first aromatization catalyst 112 canhave a first surface area in a range from about 85 m²/g to about 140m²/g, or from about 90 m²/g to about 145 m²/g, and a first microporevolume in a range from about 0.01 cc/g to about 0.045 cc/g, from about0.015 cc/g to about 0.045 cc/g, or from about 0.02 cc/g to about 0.04cc/g. Consistent with aspects of this invention, the first aromatizationcatalyst 112 can be a regenerated aromatization catalyst, although notlimited thereto.

Likewise, the second reactor vessel 130 contains the secondaromatization catalyst 132. The second aromatization catalyst 132 cancomprise a second transition metal and a second catalyst support, andcan be characterized by a second surface area in a range from about 160m²/g to about 260 m²/g, and a second micropore volume in a range fromabout 0.05 cc/g to about 0.09 cc/g. In some aspects, the secondaromatization catalyst 132 can have a second surface area in a rangefrom about 165 m²/g to about 240 m²/g, or from about 160 m²/g to about220 m²/g, and a second micropore volume in a range from about 0.05 cc/gto about 0.085 cc/g, from about 0.055 cc/g to about 0.09 cc/g, or fromabout 0.06 cc/g to about 0.085 cc/g. Consistent with aspects of thisinvention, the second aromatization catalyst can be a fresharomatization catalyst, although not limited thereto.

Typically, the first aromatization catalyst 112 can further contain ameasurable amount of carbon, often ranging from about 0.01 wt. % toabout 1 wt. %, from about 0.01 wt. % to about 0.5 wt. %, or from about0.02 wt. % to about 0.5 wt. %. In contrast, the second aromatizationcatalyst 132 often contains no measurable amount of carbon, i.e., lessthan 0.01 wt. %, and more often, less than 0.005 wt. %. Therefore, andconsistent with aspects of this invention, the first aromatizationcatalyst 112 can contain more carbon than does the second aromatizationcatalyst 132, often from about from about 0.01 wt. % to about 0.6 wt. %more, or from about 0.05 wt. % to about 0.5 wt. % more.

In further aspects of this invention, the first aromatization catalyst112 can contain more iron than does the second aromatization catalyst132. Additionally or alternatively, the first aromatization catalyst 112can contain more sulfur than does the second aromatization catalyst 132(e.g., the second aromatization catalyst can contain very low quantitiesof sulfur, i.e., less than 10 ppm). These comparisons are meant to bebased on the relative amounts of iron (Fe) and sulfur (S) in ppm byweight of the respective catalysts. Additionally or alternatively, thefirst aromatization catalyst 112 can contain less nitrogen (N, in ppm byweight or wt. %) than does the second aromatization catalyst 132. Insome aspects, the first aromatization catalyst 112 can contain less than0.25 wt. % N, and in further aspects, the first aromatization catalyst112 can contain no measurable amount of nitrogen

Moreover, the first aromatization catalyst 112 can be characterized by aplatinum dispersion that generally falls within a range from about 25%to about 65%, from about 25% to about 55%, or from about 30% to about50%. In contrast, the second aromatization catalyst can be characterizedby a platinum dispersion in a range from about 60% to about 75%, fromabout 60% to about 70%, or from about 65% to about 75%. Therefore, andconsistent with aspects of this invention, the first aromatizationcatalyst 112 can have a lower platinum dispersion (%) than does thesecond aromatization catalyst 132, often from about from about 5% toabout 40% less, or from about 10% to about 30% less.

Generally, the first aromatization catalyst can have a lower catalystactivity than that of the second aromatization catalyst. A lowercatalyst activity can be determined by one or more of a higher TEOR (endof run temperature), a higher TSOR (start of run temperature), and ahigher fouling rate. These performance metrics are described further inthe examples that follow.

Generally, the first aromatization catalyst has a catalyst selectivitythat is substantially the same as or better than that of the secondaromatization catalyst, i.e., the selectivity is greater than or withinabout 2 percent of the selectivity of the second aromatization catalyst.The catalyst selectivity can be the aromatics selectivity and/or thebenzene+toluene selectivity, as described further in the examples thatfollow.

While not being limited thereto, the weight ratio of the amount of thefirst aromatization catalyst 112 to the second aromatization catalyst132 in the reactor vessel system 100 can be in a range (first:second)from about 20:1 to about 1:20, from about 15:1 to about 1:15, or fromabout 10:1 to about 1:10. In some aspects, the reactor vessel system 100contains less of the first aromatization catalyst 112 than the secondaromatization catalyst 132, and in these aspects, the first:second ratiocan be in a range from about 1:1.5 to about 1:30, from about 1:2 toabout 1:20, from about 1:3 to about 1:25, or from about 1:5 to about1:15. For instance, it is contemplated that the reactor vessel system100 can contain twice as much (or three times as much, or five times asmuch, or ten times as much) of the second aromatization catalyst 132, byweight, than the first aromatization catalyst 112.

As would be recognized by those of skill in the art, the features andcharacteristics of the first aromatization catalyst and the secondaromatization catalyst (e.g., pore volume, amount of carbon, etc.) canvary as the time on stream of the reactor system increases. Forinstance, the features and characteristics of the first aromatizationcatalyst and the second aromatization catalyst can differ from start-upto after a long period of continuous production.

As it pertains to the first aromatization catalyst 112 and the secondaromatization catalyst 132, the first catalyst support and the secondcatalyst support, independently, can comprise a zeolite. For instance,large pore zeolites often can have average pore diameters in a range offrom about 7 Å to about 12 Å, and non-limiting examples of large porezeolites include L-zeolite, Y-zeolite, mordenite, omega zeolite, betazeolite, and the like. Medium pore zeolites often can have average porediameters in a range of from about 5 Å to about 7 Å. The first catalystsupport and the second catalyst support can be the same or different.

The term “zeolite” generally refers to a particular group of hydrated,crystalline aluminosilicates. These zeolites exhibit a network of SiO₄and AlO₄ tetrahedra in which aluminum and silicon atoms are crosslinkedin a three-dimensional framework by sharing oxygen atoms. In theframework, the ratio of oxygen atoms to the total of aluminum andsilicon atoms can be equal to 2. The framework exhibits a negativeelectrovalence that typically can be balanced by the inclusion ofcations within the crystal, such as metals, alkali metals, alkalineearth metals, hydrogen, or combinations thereof.

In some aspects, the first catalyst support and/or the second catalystsupport can comprise an L-type zeolite. L-type zeolite supports are asub-group of zeolitic supports, which can contain mole ratios of oxidesin accordance with the formula: M_(2/n)OAl₂O₃xSiO₂yH₂O. In this formula,“M” designates an exchangeable cation (one or more) such as barium,calcium, cerium, lithium, magnesium, potassium, sodium, strontium, zinc,or combinations thereof, as well as non-metallic cations like hydroniumand ammonium ions, which can be replaced by other exchangeable cationswithout causing a substantial alteration of the basic crystal structureof the L-type zeolite. The “n” in the formula represents the valence of“M”; “x” is 2 or greater; and “y” is the number of water moleculescontained in the channels or interconnected voids of the zeolite.

In one aspect, the first catalyst support and/or the second catalystsupport can comprise a potassium L-type zeolite, also referred to as aKL-zeolite, while in another aspect, the first catalyst support and/orthe second catalyst support can comprise a barium ion-exchangedL-zeolite. As used herein, the term “KL-zeolite” refers to L-typezeolites in which the principal cation M incorporated in the zeolite ispotassium. A KL-zeolite can be cation-exchanged (for example, withbarium) or impregnated with a transition metal and one or more halidesto produce a transition metal impregnated, halided zeolite or a KLsupported transition metal-halide zeolite catalyst.

In the first catalyst support and the second catalyst support, thezeolite can be bound with a support matrix (or binder), non-limitingexamples of which can include silica, alumina, magnesia, boria, titanic,zirconia, various clays, and the like, including mixed oxides thereof,as well as mixtures thereof. For example, the first catalyst supportand/or the second catalyst support can comprise a binder comprisingalumina, silica, a mixed oxide thereof, or a mixture thereof. Thezeolite can be bound with the binder using any method known in the art.In a particular aspect of this invention, the first catalyst support,the second catalyst support, or both the first catalyst support and thesecond catalyst support, can comprise a silica-bound KL-zeolite catalystsupport.

While not being limited thereto, the first catalyst support and thesecond catalyst support, independently, can comprise from about 5 wt. %to about 35 wt. % binder. For example, the first catalyst support andthe second catalyst support, independently, can comprise from about 5wt. % to about 30 wt. %, or from about 10 wt. % to about 30 wt. %binder. These weight percentages are based on the total weight of the(first or second) catalyst support.

The first aromatization catalyst can comprise a first transition metaland a first catalyst support, and the second aromatization catalyst cancomprise a second transition metal and a second catalyst support. Thefirst transition metal and the second transition metal can be the sameor different, and can comprise a Group 7-11 transition metal or,alternatively, a Group 8-11 transition metal. In some aspects, the firstaromatization catalyst and/or the second aromatization catalyst cancomprise a Group 14 metal such as tin, while in other aspects, the firsttransition metal and/or the second transition metal can comprise atransition metal, and non-limiting examples of suitable transitionmetals can include iron, cobalt, nickel, ruthenium, rhodium, palladium,osmium, iridium, rhenium, platinum, gold, silver, copper, and the like,or a combination of two or more transition metals.

For example, the first aromatization catalyst and/or the secondaromatization catalyst can comprise platinum, rhenium, tin, iron, gold,or any combination thereof. Alternatively, the first transition metaland/or the second transition metal can comprise a Group 7-11 transitionmetal (for example, one or more of platinum, rhenium, and gold), and inanother aspect, the first transition metal and/or the second transitionmetal can comprise a Group 10 transition metal, while in yet anotheraspect, the first transition metal and the second transition metal cancomprise platinum (Pt).

Typically, the first aromatization catalyst and the second aromatizationcatalyst can comprise from about 0.1 wt. % to about 10 wt. % transitionmetal. In another aspect, the first aromatization catalyst and/or thesecond aromatization catalyst can comprise from about 0.3 wt. % to about5 wt. % transition metal. In yet another aspect, the first aromatizationcatalyst and/or the second aromatization catalyst can comprise fromabout 0.3 wt. % to about 3 wt. % transition metal, or from about 0.5 wt.% to about 2 wt. % transition metal. These weight percentages are basedon the total weight of the (first or second) aromatization catalyst. Incircumstances where the transition metal comprises platinum, the firstaromatization catalyst and/or the second aromatization catalyst cancomprise from about 0.1 wt. % to about 10 wt. % platinum; alternatively,from about 0.3 wt. % to about 5 wt. % platinum; alternatively, fromabout 0.3 wt. % to about 3 wt. % platinum; or alternatively, from about0.5 wt. % to about 2 wt. % platinum.

In an aspect, the first aromatization catalyst, the second aromatizationcatalyst, or both, can comprise platinum on a bound L-zeolite catalystsupport. In another aspect, the first aromatization catalyst, the secondaromatization catalyst, or both, can comprise platinum on a boundKL-zeolite catalyst support. In yet another aspect, the firstaromatization catalyst, the second aromatization catalyst, or both, cancomprise platinum on a silica-bound KL-zeolite catalyst support.Accordingly, the first aromatization catalyst and the secondaromatization catalyst can be the same or different.

Additionally, the first aromatization catalyst and the secondaromatization catalyst can further comprise a halogen, such as chlorine,fluorine, bromine, iodine, or a combination of two or more halogens. Forexample, the first aromatization catalyst and/or the secondaromatization catalyst can comprise chlorine, or fluorine, or bothchlorine and fluorine.

Chlorine can be present in the first aromatization catalyst, the secondaromatization catalyst, or both, in an amount of from about 0.01 wt. %to about 5 wt. %, from about 0.1 wt. % to about 2 wt. %, or from about0.3 wt. % to about 1.3 wt. %. Likewise, the first aromatizationcatalyst, the second aromatization catalyst, or both, can comprise fromabout 0.01 wt. % to about 5 wt. % fluorine, from about 0.1 wt. % toabout 2 wt. % fluorine, or from about 0.3 wt. % to about 1.3 wt. %fluorine. These weight percentages are based on the total weight of therespective aromatization catalyst. In certain aspects, the firstaromatization catalyst, the second aromatization catalyst, or both,comprise(s) chlorine and fluorine, and typically, the molar ratio offluorine:chlorine, independently, can be in the range of from about0.2:1 to about 4:1. Other suitable molar ratios of F:Cl can include thefollowing non-limiting ranges: from about 0.3:1 to about 4:1, from about0.5:1 to about 4:1, from about 0.2:1 to about 2:1, from about 0.3:1 toabout 2:1, or from about 0.5:1 to about 2.5:1.

Examples of representative catalyst supports (e.g., zeolites andbinders) and transition metals (e.g., platinum) that can be used ascomponents of the first aromatization catalyst and/or the secondaromatization catalyst include those disclosed in U.S. Pat. Nos.5,196,631, 6,190,539, 6,406,614, 6,518,470, 6,812,180, 7,153,801, and7,932,425, the disclosures of which are incorporated herein by referencein their entirety.

As disclosed herein, aromatization reactor vessel systems encompassedherein contain at least one first reactor vessel (which can comprise onefirst reactor vessel or a series of two or more first reactor vessels)and at least one second reactor vessel (which can comprise one secondreactor vessel or a series of two or more second reactor vessels). Forexample, in addition to a system with a single first reactor vessel,exemplary reactor vessel systems can comprise any suitable number offirst reactor vessels in series, such as from 2 to 8 vessels, from 2 to4 vessels, from 2 to 3 vessels, 2 vessels, 3 vessels, or 4 vessels, inseries. Likewise, in addition to a system with a single second reactorvessel, exemplary reactor vessel systems can comprise any suitablenumber of second reactor vessels in series, such as from 2 to 8 vessels,from 2 to 6 vessels, from 2 to 4 vessels, 3 vessels, 4 vessels, 5vessels, 6 vessels, or 7 vessels, in series. The total number of reactorvessels in the aromatization reactor vessel systems is not particularlylimited, but generally includes from 2 to 12 total vessels in series,such as from 2 to 10 vessels, from 2 to 8 vessels, from 2 to 6 vessels,from 2 to 5 vessels, 3 vessels, 4 vessels, 5 vessels, 6 vessels, or 7vessels, in series. In some embodiments, the aromatization reactorvessel system encompasses a system wherein the at least one firstreactor vessel comprises from 1 to 3 first reactor vessels in series,and the at least one second reactor vessel comprises from 2 to 6 secondreactor vessels in series.

The reactor system can either be configured for a single pass of thenon-aromatic hydrocarbon through the series of reactor vessels, or thereactor system can be configured to separate the unreacted non-aromatichydrocarbons from the aromatic hydrocarbons, with subsequent recyclingof the unreacted non-aromatic hydrocarbons to the first reactor vesselin the series.

The aromatization reactor vessel system can further comprise a furnacebefore any or each reactor vessel in the series, and the furnace can becapable of heating any feed stream to a reactor vessel operatingtemperature of from about 350° C. to about 600° C. Typically, thereactor vessel system contains a furnace before the first reactor vesselin the series. Also typically, the reactor vessel system contains afurnace before each reactor vessel in the series. Each furnace can beconfigured to heat a effluent of the previous reactor vessel in theseries to a temperature of from about 350° C. to about 600° C. beforeentering the next vessel in the series. A transfer pipe can bepositioned between and connect each furnace and respective upstream anddownstream reactor vessel.

FIG. 2 presents an illustrative example of an aromatization reactorvessel system 200 containing six reactor vessels 271, 272, 273, 274,275, 276 in series, with a corresponding furnace 281, 282, 283, 284,285, 286 preceding each respective reactor vessel in the system 200. Thefurnaces 281, 282, 283, 284, 285, 286 in FIG. 2 can be capable ofheating or reheating any feed stream or effluent to a reactor vesseloperating temperature of from about 350° C. to about 600° C.

In FIG. 2, the aromatization reactor vessel system 200 contains two (2)first reactor vessels 271, 272 in series, four (4) second reactorvessels 273, 274, 275, 276 in series, and a furnace 283 positionedbetween the first reactor vessels and the second reactor vessels. Thefirst reactor vessels 271, 272 include a first reactor inlet 250 forintroducing a first hydrocarbon feed into the first reactor vessels 271,272, and a first reactor outlet 260 for discharging a first effluentthat contains a first aromatic product. As described above in relationto FIG. 1, the first aromatization catalyst is present in each firstreactor vessel.

Likewise, the second reactor vessels 273, 274, 275, 276 include a secondreactor inlet 270 for introducing a second hydrocarbon feed into thesecond reactor vessels 273, 274, 275, 276, and a second reactor outlet280 for discharging a second effluent that contains a second aromaticproduct. As described above in relation to FIG. 1, the secondaromatization catalyst is present in each second reactor vessel.

The furnace 283 is positioned between the first reactor vessels and thesecond reactor vessels as shown in FIG. 2, specifically, between thefirst reactor outlet 260 and the second reactor inlet 270. The furnace283 in FIG. 2 is capable of heating the first effluent (in the firstreactor outlet 260 from the first reactor vessels) to form the secondhydrocarbon feed (in the second reactor inlet 270 to the second reactorvessels). Generally, the furnace 283 is configured to heat the firsteffluent to a reforming temperature of any of the second reactor vessels273, 274, 275, 276, often ranging from about 350° C. to about 600° C.

A feed stream 240 can enter the first furnace 281 of the aromatizationreactor vessel system 200 shown in FIG. 2. Each reactor vessel in thesystem can be configured to contact the feed stream with anaromatization catalyst to catalytically convert at least a portion ofthe non-aromatic hydrocarbon to produce an aromatic hydrocarbon (forexample, benzene, toluene, xylenes, and the like, as well ascombinations thereof). Progressively more of the non-aromatichydrocarbon is converted to the aromatic hydrocarbon, starting with themore easily converted non-aromatic hydrocarbons, as each reactor vesselin the series has been traversed. A final effluent 280 exits the lastreactor vessel 276 in the system 200.

As an illustrative example, 10 wt. % of the total catalyst in thereactor system can be present in first reactor vessel 271, and 10 wt. %of the total catalyst can be present in first reactor vessel 272. Inthis example, the second reactor vessels 273, 274, 275, 276 can contain,respectively, 15 wt. %, 15 wt. %, 25 wt. %, and 25 wt. % of the totalcatalyst. Thus, the weight ratio of the amount of the firstaromatization catalyst to the second aromatization catalyst in thereactor vessel system (first:second) is equal to 1:4, i.e., the reactorsystem contain four times as much of the second aromatization catalystas compared to the first aromatization catalyst.

Aromatization Processes

Aspects of this invention also are directed to aromatization orreforming process. A representative aromatization process can comprise(or consist essentially of, or consist of) (i) introducing a firsthydrocarbon feed into at least one first reactor vessel comprising afirst aromatization catalyst, and contacting the first hydrocarbon feedwith the first aromatization catalyst under first reforming conditionsto produce a first aromatic product; wherein the first aromatizationcatalyst (e.g., a regenerated aromatization catalyst) comprises a firsttransition metal and a first catalyst support, the first aromatizationcatalyst characterized by a first surface area in a range from about 80m²/g to about 150 m²/g, and/or a first micropore volume in a range fromabout 0.01 cc/g to about 0.048 cc/g; (ii) discharging a first effluentcomprising the first aromatic product from the at least one firstreactor vessel; (iii) heating the first effluent to form a secondhydrocarbon feed; (iv) introducing the second hydrocarbon feed into atleast one second reactor vessel comprising a second aromatizationcatalyst, and contacting the second hydrocarbon feed with the secondaromatization catalyst under second reforming conditions to produce asecond aromatic product; wherein the second aromatization catalyst(e.g., a fresh aromatization catalyst) comprises a second transitionmetal and a second catalyst support, the second aromatization catalystcharacterized by a second surface area in a range from about 160 m²/g toabout 260 m²/g, and/or a second micropore volume in a range from about0.05 cc/g to about 0.09 cc/g; and (v) discharging a second effluentcomprising the second aromatic product from the at least one secondreactor vessel.

Generally, the features of the aromatization process (for example, thefirst and second hydrocarbon feed, the first and second aromatizationcatalyst, the first and second aromatic product, and the first andsecond surface areas and pore volumes, among others) are independentlydescribed herein and these features can be combined in any combinationto further describe the disclosed aromatization processes. Moreover,other process steps can be conducted before, during, and/or after any ofthe steps listed in this aromatization process, unless stated otherwise.

In these processes, the first hydrocarbon feed and the secondhydrocarbon feed, independently, can comprise naphtha (e.g., a mixtureof hydrocarbons obtained from the distillation of petroleum). Forinstance, the first hydrocarbon feed can comprise non-aromatichydrocarbons, such as C₆-C₉ alkanes and/or cycloalkanes, or C₆-C₈alkanes and/or cycloalkanes. Typically, the first aromatic productformed in these aromatization processes can comprise benzene, toluene,or a combination thereof.

Since aromatic hydrocarbons are produced in the first reactor vessel(s),the second hydrocarbon feed contains, in addition to non-aromatichydrocarbons, aromatic hydrocarbons formed in the first reactorvessel(s). Thus, the second hydrocarbon feed can comprise non-aromatichydrocarbons—such as C₆-C₉ alkanes and/or cycloalkanes, or C₆-C₈ alkanesand/or cycloalkanes—and aromatic hydrocarbons—such as benzene and/ortoluene. In like manner, the second aromatic product formed in thesearomatization processes can comprise benzene, toluene, or a combinationthereof.

Consistent with aspects of this invention, the first hydrocarbon feedtypically contains relatively more convertible hydrocarbons (e.g.,cyclohexane) than does the second hydrocarbon feed, when compared on amole percent basis. While not wishing to be bound by the followingtheory, it is believed that the readily converted non-aromatichydrocarbons have been converted to aromatic products in the firstreactor vessel(s), prior to entering the second reactor vessel(s).

Suitable first reforming conditions and second reforming conditions,independently, can encompass the same ranges disclosed hereinabove inrelation to the reactor vessel operating conditions. For example, thefirst reforming conditions and the second reforming conditions,independently, can comprise a reforming temperature in a range fromabout 350° C. to about 600° C. (or from about 400° C. to about 600° C.)and a reforming pressure in a range from about 20 psig (138 kPag) toabout 150 psig (1034 kPag) (or from about 70 psig to about 120 psig(about 483 kPag to about 827 kPag)). While not required, often thereforming pressure in the first reactor vessel(s) is higher than in thesecond reactor vessel(s).

While not wishing to be bound by the following theory, it is believedthat the first reforming conditions can include a lower H₂:hydrocarbonmolar ratio than that utilized in the second reforming conditions, andthat this difference can be due to hydrogen generation in the firstreactor vessel(s).

Other suitable non-aromatic hydrocarbon feed materials, aromatichydrocarbon products, and aromatization or reforming conditions for usein the disclosed process can be found, for example, in U.S. Pat. Nos.4,456,527, 5,389,235, 5,401,386, 5,401,365, 6,207,042, 7,932,425, and9,085,736, the disclosures of which are incorporated herein by referencein their entirety.

Referring now to the first aromatization catalyst and the secondaromatization catalyst used in the disclosed aromatization processes,the first catalyst support and the second catalyst support can be thesame or different and, independently, can be any of the catalystsupports disclosed herein as being suitable catalyst support materialsfor use in the first or second aromatization reactor vessels. Forexample, the first catalyst support and/or the second catalyst supportcan comprise a silica-bound KL-zeolite. Likewise, the first transitionmetal and the second transition metal, independently, can be any of thetransition metals disclosed herein as being suitable transition metalsfor use in the first or second aromatization reactor vessels. Forexample, the first transition metal and the second transition metal cancomprise platinum. Accordingly, the first aromatization catalyst and thesecond aromatization catalyst, independently, can comprise any suitableweight percentage of transition metal (or platinum) or an amount oftransition metal (or platinum) in any range disclosed herein, forexample, from about 0.1 wt. % to about 10 wt. %, from about 0.3 wt. % toabout 5 wt. %, or from about 0.5 wt. % to about 2 wt. %, based on thetotal weight of the respective aromatization catalyst.

In one aspect, the first aromatization catalyst and/or the secondaromatization catalyst can comprise platinum on a bound L-zeolitecatalyst support, while in another aspect, the first aromatizationcatalyst and/or the second aromatization catalyst can comprise platinumon a bound KL-zeolite catalyst support, and in yet another aspect, thefirst aromatization catalyst and/or the second aromatization catalystcan comprise platinum on a silica-bound KL-zeolite catalyst support.

Independently, the first aromatization catalyst and the secondaromatization catalyst can further comprise a halogen, such as chlorineand/or fluorine. Suitable amounts are disclosed herein, and often rangefrom about 0.01 wt. % to about 5 wt. %, or from about 0.3 to about 1.3wt. %, of fluorine and chlorine individually. The relative amount offluorine and chlorine on the respective catalyst also is disclosedherein, and generally falls within a molar ratio range offluorine:chlorine (F:Cl) from about 0.2:1 to about 4:1.

The first aromatization catalyst generally has less surface area andpore volume than the second aromatization catalyst. For instance, thefirst aromatization catalyst can have a surface area in a range fromabout 80 m²/g to about 150 m²/g, from about 85 m²/g to about 140 m²/g,or from about 90 m²/g to about 145 m²/g, while the second aromatizationcatalyst can have a surface area that typically falls within a rangefrom about 160 m²/g to about 260 m²/g, from about 165 m²/g to about 240m²/g, or from about 160 m²/g to about 220 m²/g. Similarly, the firstmicropore volume of the first aromatization catalyst can be from about0.01 cc/g to about 0.048 cc/g, from about 0.01 cc/g to about 0.045 cc/g,from about 0.015 cc/g to about 0.045 cc/g, or from about 0.02 cc/g toabout 0.04 cc/g, while the second micropore volume of the secondaromatization catalyst typically falls within a range from about 0.05cc/g to about 0.09 cc/g, from about 0.05 cc/g to about 0.085 cc/g, fromabout 0.055 cc/g to about 0.09 cc/g, or from about 0.06 cc/g to about0.085 cc/g.

Furthermore, as described herein, the first aromatization catalyst oftencontains relatively more carbon (in wt. %), relatively more iron (in ppmby weight), relatively more sulfur (in ppm by weight), and/or relativelyless nitrogen (in ppm by weight), than does the second aromatizationcatalyst. Additionally or alternatively, the first aromatizationcatalyst can be characterized by a lower platinum dispersion than thatof the second aromatization catalyst.

Generally, the first aromatization catalyst can have a lower catalystactivity than that of the second aromatization catalyst. A lowercatalyst activity can be determined by one or more of a higher TEOR (endof run temperature), a higher TSOR (start of run temperature), and ahigher fouling rate. These performance metrics are described further inthe examples that follow.

Generally, the first aromatization catalyst has a catalyst selectivitythat is substantially the same as or better than that of the secondaromatization catalyst, i.e., the selectivity is greater than or withinabout 2 percent of the selectivity of the second aromatization catalyst.The catalyst selectivity can be the aromatics selectivity and/or thebenzene+toluene selectivity, as described further in the examples thatfollow. Moreover, any comparisons are meant to be performed under thesame test conditions.

As would be recognized by those of skill in the art, the features andcharacteristics of the first aromatization catalyst and the secondaromatization catalyst (e.g., pore volume, amount of carbon, etc.) canvary as the process is conducted for longer periods of time. Forinstance, the features and characteristics of the first aromatizationcatalyst and the second aromatization catalyst can differ from thestart-up phase of the process to after a long period of continuousoperation of the process.

While not being limited thereto, the weight ratio of the amount of thefirst aromatization catalyst to the second aromatization catalyst in thearomatization process (first:second) can range from about 20:1 to about1:20, from about 15:1 to about 1:15, or from about 10:1 to about 1:10.However, the aromatization process can be conducted with significantlyless of the first aromatization catalyst, as compared to the amount ofthe second aromatization catalyst, such that the first:second ratio canbe in a range from about 1:1.5 to about 1:30, from about 1:2 to about1:20, from about 1:3 to about 1:25, or from about 1:5 to about 1:15.

The aromatization process can be conducted with at least one firstreactor vessel (which can comprise one first reactor vessel or a seriesof two or more first reactor vessels) and at least one second reactorvessel (which can comprise one second reactor vessel or a series of twoor more second reactor vessels). For example, in addition a single firstreactor vessel, the process can be performed with from 2 to 8 firstreactor vessels, from 2 to 4 first reactor vessels, or from 2 to 3 firstreactor vessels, in series. Likewise, in addition to a single secondreactor vessel, the process can be performed with from 2 to 8 secondreactor vessels, from 2 to 6 second reactor vessels, or from 2 to 4second reactor vessels, in series.

The aromatization process is not limited by the reactor type. In oneaspect, for instance, the first reactor vessel(s) and the second reactorvessel(s) can be radial flow reactors. Alternatively, the first reactorvessel(s) and the second reactor vessel(s) can be traditional packed bed(or fixed bed) reactors. Any hydrocarbon feed or effluent in thearomatization process can be heated to typical reforming temperatureswith any suitable apparatus, such as a furnace.

EXAMPLES

The invention is further illustrated by the following examples, whichare not to be construed in any way as imposing limitations to the scopeof this invention. Various other aspects, modifications, and equivalentsthereof, which after reading the description herein, can suggestthemselves to one of ordinary skill in the art without departing fromthe spirit of the present invention or the scope of the appended claims.

Sulfur content was measured by inductively coupled plasma spectroscopy(ICP). Surface areas were determined using the Brunauer, Emmett, andTeller (“BET”) method, described in Brunauer, Stephen; Emmett, P. H.;Teller, Edward (1938), “Adsorption of Gases in Multimolecular Layers,”Journal of the American Chemical Society, 60 (2): 309-319,doi:10.1021/ja01269a023, which is incorporated herein by reference inits entirety. Micropore volumes were determined using the t-plot methodusing the thickness equation of Harkins and Jura. The t-plot method isdescribed by Lippens and de Boer in Lippens B. C., and de Boer J. H.,(1965), J. Catal. 4, 319; and De Boer J. H. Lippens B. C, Linsen B. G.,Broeckhoff J. C. P., van den Heuvel A., and Onsinga T. V., (1966), J.Colloid Interf. Sci. 21, 405, each of which is incorporated herein byreference in its entirety. The thickness equation of Harkins and Jura ispublished in the Journal of the American Chemical Society, 66, 1366(1944), which is incorporated herein by reference in its entirety. Asused herein, micropores are defined as pores having pore diameters lessthan 2 nm, mesopores are defined as having pore diameters between 2 and50 nm, and macropores are defined as pores having pore diameters greaterthan 50 nm. Platinum dispersion was determined by CO chemisorption.

Weight percentages of Pt, Cl, F, and Fe were determined using X-rayfluorescence (XRF), and are based on the total weight of thearomatization catalyst, unless stated otherwise. Carbon (wt. %) wasdetermined by CHNS analyzer (Carlo Erba).

Examples 1-2

The fresh aromatization catalyst of Example 1 was a Pt/KL-zeolitecontaining approximately 1 wt. % platinum, 0.7-0.9 wt. % Cl and 0.7-0.9wt. % F, and having a BET surface area of approximately 178 m²/g and amicropore volume of 0.062 cc/g.

For use in Example 2, the fresh catalyst of Example 1 was deactivatedafter contact with sulfur to form a sulfur-contaminated catalyst (a“spent” catalyst) containing 178 ppm by weight of sulfur. Prior to usein Example 2, the sulfur-contaminated aromatization catalyst wassubjected to a hydrocarbon removal treatment to remove unreactedhydrocarbons and some light carbonaceous deposits from thesulfur-contaminated catalyst.

To regenerate the spent catalyst in Example 2, 100 g of thesulfur-contaminated catalyst were washed with deionized water containingKCl (0.1 M). The washing conditions consisted of 3 wash cycles, eachconducted at 100° F. for 20 minutes with the weight of the wash water(excluding KCl) being 2.5 times the weight of the catalyst. The washingwas performed batchwise with N₂ bubbling to agitate the mixture. Thewashed catalyst was next dried at 250° F. for 4 hours and calcined at900° F. for 1 hour under air flow. For the halogenation step, 1.43 g ofammonium chloride and 1.82 g of ammonium fluoride were dissolved into 35mL of deionized water. Next, 100 g of the washed catalyst wereimpregnated with the halogen solution. The impregnated material wasallowed to soak for 4 hours at room temperature. It was then dried at 43torr and 38° C. for 2 hours. The temperature was then increased to 95°C. for 1 hour. Lastly, the catalyst of Example 2 was calcined in flowingair at 900° F. for 1 hour.

For Example 1 and Example 2, the following standard testing procedureswere utilized. The respective catalysts were ground and sieved to 25-45mesh and 0.69 g (˜1 cc) of the sieved catalyst was placed in a ⅜-inch ODstainless steel reactor vessel in a temperature controlled furnace.After reducing the catalyst under flowing molecular hydrogen, a feedstream of aliphatic hydrocarbons (12 mL/min) and molecular hydrogen (43mL/min) was introduced to the reactor vessel at a pressure of 100 psig,a H₂:hydrocarbon molar ratio of 1.3, and a liquid hourly space velocity(LHSV) of 12 hr⁻¹ to obtain catalyst performance data over time. Thehydrocarbon feed contained from 22 to 26 wt. % n-hexane, 4 to 8 wt. %n-heptane, 33 to 37 wt. % C₆ iso-paraffins, 15 to 21 wt. % C₇iso-paraffins, 6 to 10 wt. % C₈ iso-paraffins, with the balanceattributable to C₆ and C₇ olefins, naphthenes, C₅-species, andaromatics. The reactor effluent composition was analyzed by gaschromatography (using a capillary column and a flame ionizationdetector) to determine the amount of aromatics, such as benzene andtoluene.

The catalysts of Example 1 and Example 2 were tested for theirrespective fouling rates (abbreviated FR, units of ° F./hr), whichcorrelate to their activities by the formula, y=FR*t+TSOR, where y istemperature, FR is the fouling rate, t is time, and TSOR is the initialStart of Run temperature. The FR of a catalyst sample was determined byplotting the temperature (yield adjusted catalyst temperature) requiredto maintain a total yield of aromatics (such as benzene and toluene) at63 wt. % over time at standard test conditions, as described above. TheFR's were then determined from the calculated slopes fit to theresulting data using linear regression. The total time on stream was 40hours, and the End of Run temperature (abbreviated TEOR) at 40 hoursalso was determined. In order to exclude the catalyst break-in period,only data from 15+hours online was included in the TSOR and FRcalculations.

FIG. 3 and FIG. 4, respectively, compare the aromatics selectivity andyield adjusted catalyst temperature versus the reaction time for thecatalysts of Example 1 (fresh) and Example 2 (regenerated catalyst).Table I summarizes certain properties of the catalysts of Examples 1-2and relevant performance metrics from FIGS. 3-4.

Notably, the regenerated catalyst of Example 2 had an aromaticsselectivity equivalent to or better than that of the fresh catalyst ofExample 1, despite having significantly lower surface area and microporevolume. The catalyst activity of Example 1 was superior to that ofExample 2: lower TSOR, lower TEOR, and lower fouling rate. Examples 1-2demonstrate that, while the catalyst selectivity was restored viaregeneration (even with sulfur contamination), the catalyst activity ofthe regenerated catalyst was not equivalent to that of the freshcatalyst.

TABLE I Examples 1-2. Example 1 2 Catalyst Fresh Regenerated PlatinumDispersion (%) 67 35 Surface Area (m²/g) 178 100 Micropore Volume (cc/g)0.062 0.026 Sulfur (ppmw) N/A 107 Aromatics Yield at 1000° F. >63% >63%TSOR (° F.) 939 977 TEOR (° F.) 942 985 Fouling Rate (° F./hr) 0.05 0.23

Examples 3-5

The fresh aromatization catalyst of Example 3 was a Pt/KL-zeolitecontaining approximately 1 wt. % platinum, 0.83 wt. % Cl and 0.84 wt. %F, and having a BET surface area of approximately 177 m²/g, a totalnitrogen pore volume of 0.19 cc/g, and a micropore volume of 0.062 cc/g.

For use in Examples 4-5, the fresh catalyst of Example 3 was deactivatedafter long-term use in an aromatization process (a “spent” catalyst).Prior to use in Examples 4-5, the spent catalyst was subjected to ahydrocarbon removal treatment to remove unreacted hydrocarbons and somelight carbonaceous deposits from the spent catalyst.

To regenerate the spent catalyst in Example 4, the spent catalyst wasdried under nitrogen at 400° F. (204° C.) for 16 hours (GHSV=1500 hr⁻¹).Chlorine diluted in a nitrogen gas stream (0.9 vol. % CO was added tothe dried spent catalyst at 300° F. (149° C.) over 3 hours. After thechlorination step was complete, the chlorinated spent catalyst waspurged at 400° F. (204° C.) with nitrogen for 16 hours. After purging,nitrogen gas was replaced by a mixture of air and nitrogen (1 vol. %oxygen). The catalyst was heated up to 750° F. (340° C.) for 44 hoursusing a 0.8° F./min ramp (0.4° C./min). After the carbon burn step,fluorine was added in the liquid phase. First, 0.69 g of ammoniumfluoride was dissolved into 13 mL of deionized water, then 38 g of thechlorinated and de-coked catalyst was impregnated with thefluorine-containing solution at ambient temperature, followed by restingthe impregnated catalyst for 4 hours. The fluorinated catalyst was driedfor 3 hours under vacuum at a maximum temperature of 95° C., followed bycalcination at 900° F. (482° C.) in air for 1 hour.

For Examples 3 and Example 4, the following standard testing procedureswere utilized. The respective catalysts were ground and sieved to 25-45mesh, and 1 cc of the sieved catalyst was placed in a ⅜inch OD stainlesssteel reactor vessel in a temperature controlled furnace. After reducingthe catalyst under flowing molecular hydrogen, a feed stream ofaliphatic hydrocarbons and molecular hydrogen was introduced to thereactor vessel at a pressure of 100 psig, a H₂:hydrocarbon molar ratioof 1.3:1, and a liquid hourly space velocity (LHSV) of 12 hr⁻¹ to obtaincatalyst performance data over time. The aliphatic hydrocarbon feedcontained approximately 0.61 mole fraction of convertible C₆ species and0.21 mole fraction of convertible C₇ species. The balance was attributedto aromatics, C₈ ⁺, and highly branched isomers, which are classified asnon-convertibles. The reactor effluent composition was analyzed by gaschromatography to determine the total aromatics and the aromaticsselectivity.

Catalyst activity was quantified by the temperature needed to obtain adefined aromatics yield of 63 wt. % in C₅ ⁺. The temperatures were thenplotted versus time to evaluate catalyst activity performance over time.Lower temperatures, therefore, demonstrate a more active catalyst.Selectivity to aromatics (mol/mol) was calculated and also used tocompare catalyst selectivity over time.

FIG. 5 illustrates that full catalyst activity can be restored for someregenerated catalysts: the catalyst activities for the fresh catalyst ofExample 3 and the regenerated catalyst of Example 4 were substantiallythe same. Specifically, FIG. 5 shows that the same temperature wasneeded for both the fresh catalyst of Example 3 and the regeneratedcatalyst of Example 4 to achieve the same aromatics yield (63 wt. % inC₅ ⁺) throughout the 40-hr experiment, indicating that the freshcatalyst and the regenerated catalyst had substantially the samecatalyst activity. FIG. 6 illustrates that the catalyst selectivity ofthe regenerated catalyst of Example 4 was comparable to, or better than,that of the fresh catalyst of Example 3. Specifically, FIG. 6 showsaromatics selectivity in the 90-94% range for the regenerated catalystof Example 4 throughout the 40-hr experiment, which was slightly betterthan that of the fresh catalyst.

To regenerate the spent catalyst in Example 5, both chlorination andfluorination steps were performed in the liquid phase. First, 1.43 g ofammonium chloride and 1.82 g of ammonium fluoride were dissolved in 30mL of deionized water, then 100 g of the spent catalyst was impregnatedwith the chlorine/fluorine-containing solution. The impregnated materialwas then vacuum dried at a maximum temperature of 95° C., followed bycalcination in air at 900° F. (482° C.) for 1 hour using a 550° F./hramp (288° C./h). The regenerated catalyst of Example 5 was then testedin the aromatization reaction using the same procedure as Examples 3-4.FIGS. 7-8 demonstrate that selectivity was restored to the regeneratedcatalyst of Example 5, but the activity of the regenerated catalyst ofExample 5 was far less than that of the fresh catalyst of Example 3(˜20-25° F. higher temperatures were needed to achieve 63 wt. %aromatics yield).

Certain properties of the catalysts of Examples 3-5 are summarized inTable II. In sum, the data from FIGS. 5-8 and Table II indicate that thecatalyst selectivity was restored via regeneration, but the catalystactivity was not always recoverable. Interestingly, despite the muchlower platinum dispersion and micropore volume values for Examples 4-5,the catalyst selectivity for Examples 4-5 was comparable to, if notbetter than that of the fresh catalyst of Example 3.

TABLE II Examples 3-5. Property Example 5 Example 4 Example 3 Microporevolume (cc/g) 0.038 0.030 0.062 Pt Dispersion (%) 38 48 67 Carbon (wt.%) 0.01 0.02 0.01 Fluorine (wt. %) 0.69 0.63 0.84 Chlorine (wt. %) 0.890.89 0.83

Examples 6-7

The fresh aromatization catalyst of Example 6 was a Pt/KL-zeolitecontaining approximately 1 wt. % platinum, 0.85 wt. % Cl, and 0.70 wt. %F, and having a BET surface area of approximately 177.5 m²/g, a totalnitrogen pore volume of 0.19 cc/g, and a micropore volume of 0.0615cc/g.

For use in Example 7, the fresh catalyst of Example 6 was deactivatedafter long-term use in an aromatization process (a “spent” catalyst).Prior to use in Example 7, the spent catalyst was subjected to ahydrocarbon removal treatment to remove unreacted hydrocarbons and somelight carbonaceous deposits from the spent catalyst.

Example 7 used the following regeneration procedure. Approximately 42 gof the spent catalyst was charged to a new metal fixed-bed reactor(stainless steel 347), then contacted at 400° F. with a nitrogen gasstream (1500 mL/min) for 12 hr, then contacted at 400° F. with achlorine-containing gas stream containing nitrogen (1463 mL/min) andchlorine gas (37 mL/min) for 3 hr, then contacted at 400° F. with anitrogen gas stream (1463 mL/min) for 3 hr, then contacted at 750° F.with a decoking gas stream containing a mixture of air (75 mL/min) andnitrogen (1425 mL/min) for 44 hr, then contacted at 400° F. with afluorine-containing gas stream containing nitrogen (1350 mL/min) andfluorine gas (147 mL/min) for 3 hr, and then contacted at 400° F. with anitrogen gas stream (1353 mL/min) for 3 hr.

For Example 6 and Example 7, the following standard testing procedureswere utilized. The catalysts were ground and sieved to about 25-45 mesh,and 1 g of the sieved catalyst was placed in a ¼-inch OD stainless steelreactor vessel in a temperature controlled furnace. After reducing thecatalyst under flowing molecular hydrogen, a feed stream of aliphatichydrocarbons and molecular hydrogen was introduced to the reactor vesselat a feed rate of 22 mL/min, a pressure of 100 psig, a H₂:hydrocarbonmolar ratio of 1.3:1, and a liquid hourly space velocity (LHSV) of 12hr⁻¹ to obtain catalyst performance data over time. The aliphatichydrocarbon feed contained from 22 to 26 wt. % n-hexane, 4 to 8 wt. %n-heptane, 33 to 37 wt. % C₆ iso-paraffins, 17 to 21 wt. % C₇iso-paraffins, 6 to 10 wt. % C₈ iso-paraffins, with the balanceattributable to C₆ and C₇ olefins, naphthenes, and aromatics. Thereactor effluent composition was analyzed by gas chromatography todetermine the total aromatics and the benzene+toluene selectivity.

Catalyst activity and selectivity were monitored over a 40-hr experimentin which the temperature was adjusted to maintain a total aromaticsyield at 63 wt. % over time at the standard test conditions, asdescribed above.

FIG. 9 and FIG. 10 are plots of the yield adjusted temperature versusreaction time and the benzene+toluene selectivity versus reaction time,respectively, for the regenerated catalyst of Example 7 compared withthe fresh catalyst of Example 6 and the spent catalyst. Table IIIsummarizes certain properties of the regenerated catalyst of Example 7.In Table III, the amounts of Cl and F on the regenerated catalyst are inwt. %, the amount of carbon is in wt. %, and the amount of iron is inppmw (ppm by weight). The fresh catalyst of Example 6 containedsubstantially no carbon and iron. After the regeneration process, thecatalyst bed was split into four layers: Layer 1 was the top layer,Layer 4 was the bottom layer, and a composite was a physical mix ofLayers 1-4.

In sum, the data from FIGS. 9-10 and Table III indicate that selectivitywas restored via regeneration, but the activity of the regeneratedcatalyst was not equivalent to that of the fresh catalyst (highertemperatures were required to achieve the same aromatics yield).Interestingly, despite the iron and carbon levels of the regeneratedcatalyst of Example 7, the benzene+toluene selectivity for Example 7 wascomparable to, if not better than that of the fresh catalyst of Example6.

TABLE III Example 7. Cl F Fe Carbon Layer (wt. %) (wt. %) (ppmw) (wt. %)Layer 1 0.86 2.29 200 0.10 Layer 2 0.95 1.06 189 0.07 Layer 3 0.95 0.62190 0.08 Layer 4 0.94 0.12 195 0.12

The invention is described above with reference to numerous aspects andspecific examples. Many variations will suggest themselves to thoseskilled in the art in light of the above detailed description. All suchobvious variations are within the full intended scope of the appendedclaims. Other aspects of the invention can include, but are not limitedto, the following (aspects are described as “comprising” but,alternatively, can “consist essentially of” or “consist of”):

Aspect 1. An aromatization process comprising:

(i) introducing a first hydrocarbon feed into at least one first reactorvessel comprising a first aromatization catalyst, and contacting thefirst hydrocarbon feed with the first aromatization catalyst under firstreforming conditions to produce a first aromatic product; wherein:

the first aromatization catalyst comprises a first transition metal anda first catalyst support, the first aromatization catalyst characterizedby:

a first surface area in a range from about 80 m²/g to about 150 m²/g;and/or a first micropore volume in a range from about 0.01 cc/g to about0.048 cc/g;

(ii) discharging a first effluent comprising the first aromatic productfrom the at least one first reactor vessel;

(iii) heating the first effluent to form a second hydrocarbon feed;

(iv) introducing the second hydrocarbon feed into at least one secondreactor vessel comprising a second aromatization catalyst, andcontacting the second hydrocarbon feed with the second aromatizationcatalyst under second reforming conditions to produce a second aromaticproduct; wherein:

the second aromatization catalyst comprises a second transition metaland a second catalyst support, the second aromatization catalystcharacterized by:

a second surface area in a range from about 160 m²/g to about 260 m²/g;and/or a second micropore volume in a range from about 0.05 cc/g toabout 0.09 cc/g; and

(v) discharging a second effluent comprising the second aromatic productfrom the at least one second reactor vessel.

Aspect 2. The process of aspect 1, wherein the first aromatizationcatalyst has a first surface area in any range disclosed herein (e.g.,from about 85 m²/g to about 140 m²/g), and the second aromatizationcatalyst has a second surface area in any range disclosed herein (e.g.,from about 165 m²/g to about 240 m²/g).

Aspect 3. The process of any one of the preceding aspects, wherein thefirst aromatization catalyst has a first micropore volume in any rangedisclosed herein (e.g., from about 0.015 cc/g to about 0.045 cc/g), andthe second aromatization catalyst has a second micropore volume in anyrange disclosed herein (e.g., from about 0.055 cc/g to about 0.09 cc/g).

Aspect 4. The process of any one of the preceding aspects, wherein thefirst aromatization catalyst contains more carbon (e.g., from about 0.01wt. % to about 0.6 wt. % more carbon) than that of the secondaromatization catalyst.

Aspect 5. The process of any one of the preceding aspects, wherein thefirst aromatization catalyst is further characterized by an amount ofcarbon in any range disclosed herein (e.g., from about 0.01 to about 1wt. %), and the second aromatization catalyst is further characterizedby an amount of carbon in any range disclosed herein (e.g., less than0.01 wt. %, or no measurable amount).

Aspect 6. The process of any one of the preceding aspects, wherein thefirst aromatization catalyst contains less nitrogen (ppmw) than that ofthe second aromatization catalyst (e.g., the first aromatizationcatalyst may contain no measurable amount of nitrogen), and/or the firstaromatization catalyst contains more sulfur (ppmw) than that of thesecond aromatization catalyst (e.g., the second aromatization catalystmay contain less than 10 ppm of sulfur).

Aspect 7. The process of any one of the preceding aspects, wherein thefirst aromatization catalyst contains more iron (Fe, ppmw) than that ofthe second aromatization catalyst.

Aspect 8. The process of any one of the preceding aspects, wherein thefirst aromatization catalyst has a lower platinum dispersion (e.g., from10% to 30% lower) than that of the second aromatization catalyst.

Aspect 9. The process of any one of the preceding aspects, wherein thefirst aromatization catalyst is further characterized by a platinumdispersion in any range disclosed herein (e.g., from about 25% to about65%, or from about 30% to about 50%), and the second aromatizationcatalyst is further characterized by a platinum dispersion in any rangedisclosed herein (e.g., from about 60% to about 75%).

Aspect 10. The process of any one of the preceding aspects, wherein thefirst aromatization catalyst has a lower catalyst activity than that ofthe second aromatization catalyst.

Aspect 11. The process of any one of the preceding aspects, wherein thefirst aromatization catalyst has a catalyst selectivity that issubstantially the same as or better than that of the secondaromatization catalyst.

Aspect 12. The process of any one of the preceding aspects, wherein aweight ratio the first aromatization catalyst to the secondaromatization catalyst in the aromatization process is in any range offirst:second disclosed herein, e.g., from about 1:1.5 to about 1:30,from about 1:2 to about 1:20, or from about 1:5 to about 1:15.

Aspect 13. The process of any one of the preceding aspects, wherein theat least one first reactor vessel and the at least one second reactorvessel are radial flow reactors.

Aspect 14. The process of any one of the preceding aspects, wherein theat least one first reactor vessel comprises a number of reactor vesselsin any range disclosed herein (e.g., from 1 to 3 first reactor vesselsin series), and the at least one second reactor vessel comprises anumber of reactor vessels in any range disclosed herein (e.g., from 2 to6 second reactor vessels in series).

Aspect 15. The process of any one of the preceding aspects, wherein thefirst hydrocarbon feed and the second hydrocarbon feed, independently,comprise naphtha.

Aspect 16. The process of any one of the preceding aspects, wherein thefirst hydrocarbon feed comprises non-aromatic hydrocarbons, e.g., C₆-C₉alkanes and/or cycloalkanes, or C₆-C₈ alkanes and/or cycloalkanes.

Aspect 17. The process of any one of the preceding aspects, wherein thefirst aromatic product comprises benzene, toluene, or a combinationthereof.

Aspect 18. The process of any one of the preceding aspects, wherein thesecond hydrocarbon feed comprises non-aromatic hydrocarbons (e.g., C₆-C₉alkanes and/or cycloalkanes, or C₆-C₈ alkanes and/or cycloalkanes) andaromatic hydrocarbons (e.g., benzene and/or toluene).

Aspect 19. The process of any one of the preceding aspects, wherein thesecond aromatic product comprises benzene, toluene, or a combinationthereof.

Aspect 20. The process of any one of the preceding aspects, wherein thefirst hydrocarbon feed contains more convertible hydrocarbons (e.g.,cyclohexane) than the second hydrocarbon feed, on a mole percent basis.

Aspect 21. The process of any one of the preceding aspects, wherein thefirst reforming conditions and the second reforming conditions,independently, comprise a reforming temperature in any reformingtemperature range disclosed herein, e.g., from about 350° C. to about600° C., or from about 400° C. to about 600° C.

Aspect 22. The process of any one of the preceding aspects, wherein thefirst reforming conditions and the second reforming conditions,independently, comprise a reforming pressure in any reforming pressurerange disclosed herein, e.g., from about 20 to about 100 psig.

Aspect 23. The process of any one of the preceding aspects, wherein thefirst reforming conditions comprise a higher reforming pressure than thesecond reforming conditions.

Aspect 24. The process of any one of the preceding aspects, wherein thefirst reforming conditions comprise a lower H₂:hydrocarbon molar ratiothan the second reforming conditions.

Aspect 25. The process of any one of the preceding aspects, wherein thefirst catalyst support and the second catalyst support, independently,comprise a zeolite.

Aspect 26. The process of any one of the preceding aspects, wherein thefirst catalyst support and the second catalyst support, independently,comprise an L-zeolite, a Y-zeolite, a mordenite, an omega zeolite,and/or a beta zeolite.

Aspect 27. The process of any one of the preceding aspects, wherein thefirst catalyst and the second catalyst support, independently, comprisea potassium L-zeolite or a barium ion-exchanged L-zeolite.

Aspect 28. The process of any one of the preceding aspects, wherein thefirst catalyst support and the second catalyst support, independently,comprise a binder comprising alumina, silica, a mixed oxide thereof, ora mixture thereof.

Aspect 29. The process of any one of the preceding aspects, wherein thefirst catalyst support and the second catalyst support, independently,comprise any weight percentage of binder disclosed herein, e.g., fromabout 3 wt. % to about 35 wt. %, or from about 5 wt. % to about 30 wt. %binder, based on the total weight of the respective catalyst support.

Aspect 30. The process of any one of the preceding aspects, wherein thefirst catalyst support and the second catalyst support, independently,comprise a silica-bound KL-zeolite catalyst support.

Aspect 31. The process of any one of the preceding aspects, wherein thefirst transition metal and the second transition metal, independently,comprise a Group 7-11 transition metal, or a Group 8-11 transitionmetal.

Aspect 32. The process of any one of the preceding aspects, wherein thefirst transition metal and the second transition metal, independently,comprise platinum, rhenium, gold, or combinations thereof.

Aspect 33. The process of any one of the preceding aspects, wherein thefirst transition metal and the second transition metal compriseplatinum.

Aspect 34. The process of any one of the preceding aspects, wherein thefirst aromatization catalyst and the second aromatization catalyst,independently, comprise any weight percentage range of (first or second)transition metal disclosed herein, e.g., from about 0.1 wt. % to about10 wt. %, or from about 0.3 wt. % to about 5 wt. %, transition metal.

Aspect 35. The process of any one of the preceding aspects, wherein thefirst aromatization catalyst and the second aromatization catalyst,independently, comprise any weight percentage range of platinumdisclosed herein, e.g., from about 0.1 wt. % to about 10 wt. %, or fromabout 0.5 wt. % to about 2 wt. %, platinum.

Aspect 36. The process of any one of the preceding aspects, wherein thefirst aromatization catalyst and the second aromatization catalyst,independently, comprise platinum on a bound L-zeolite catalyst support.

Aspect 37. The process of any one of the preceding aspects, wherein thefirst aromatization catalyst and the second aromatization catalyst,independently, comprise platinum on a bound KL-zeolite catalyst support.

Aspect 38. The process of any one of the preceding aspects, wherein thefirst aromatization catalyst and the second aromatization catalyst,independently, comprise platinum on a silica-bound KL-zeolite catalystsupport.

Aspect 39. The process of any one of the preceding aspects, wherein thefirst aromatization catalyst and the second aromatization catalystfurther comprise chlorine and fluorine.

Aspect 40. The process of any one of the preceding aspects, wherein thefirst aromatization catalyst and the second aromatization catalyst,independently, comprise any weight percentage range of chlorine and/orweight percentage range of fluorine disclosed herein, e.g., from about0.01 wt. % to about 5 wt. %, or from about 0.3 to about 1.3 wt. %fluorine, and/or from about 0.01 wt. % to about 5 wt. %, or from about0.3 to about 1.3 wt. % chlorine.

Aspect 41. The process of any one of the preceding aspects, wherein thefirst aromatization catalyst and the second aromatization catalyst,independently, comprise any molar ratio of fluorine:chlorine disclosedherein, e.g., from about 0.2:1 to about 4:1.

Aspect 42. The process of any one of the preceding aspects, whereinheating the first effluent is performed in any suitable apparatus, e.g.,a furnace.

Aspect 43. The process of any one of the preceding aspects, wherein theat least one first reactor vessel comprises two or more reactor vesselsin series, with a furnace between each reactor vessel.

Aspect 44. The process of any one of the preceding aspects, wherein theat least one second reactor vessel comprises two or more reactor vesselsin series, with a furnace between each reactor vessel.

Aspect 45. An aromatization reactor vessel system comprising:

(A) at least one first reactor vessel comprising:

(a1) a first reactor inlet for introducing a first hydrocarbon feed intothe at least one first reactor vessel;

(a2) a first aromatization catalyst for catalytically converting atleast a portion of the first hydrocarbon feed under first reformingconditions to produce a first aromatic product; wherein the firstaromatization catalyst comprises a first transition metal and a firstcatalyst support; the first aromatization catalyst characterized by:

a first surface area in a range from about 80 m²/g to about 150 m²/g;and/or

a first micropore volume in a range from about 0.01 cc/g to about 0.048cc/g; and

(a3) a first reactor outlet for discharging a first effluent comprisingthe first aromatic product from the at least one first reactor vessel;

(B) at least one second reactor vessel comprising:

(b1) a second reactor inlet for introducing a second hydrocarbon feedinto the at least one second reactor vessel;

(b2) a second aromatization catalyst for catalytically converting atleast a portion of the second hydrocarbon feed under second reformingconditions to produce a second aromatic product; wherein the secondaromatization catalyst comprises a second transition metal and a secondcatalyst support, the second aromatization catalyst characterized by:

a second surface area in a range from about 160 m²/g to about 260 m²/g;and/or a second micropore volume in a range from about 0.05 cc/g toabout 0.09 cc/g; and

(b3) a second reactor outlet for discharging a second effluentcomprising the second aromatic product from the at least one secondreactor vessel; and

(C) a furnace positioned between the first reactor outlet and the secondreactor inlet, the furnace capable of heating the first effluent to formthe second hydrocarbon feed.

Aspect 46. The system of aspect 45, wherein the at least one firstreactor vessel and the at least one second reactor vessel,independently, comprise stainless steel.

Aspect 47. The system of aspect 45 or 46, wherein the at least one firstreactor vessel and the at least one second reactor vessel,independently, are configured for an operating pressure in any suitablerange or in any range disclosed herein, e.g., at least 20 psig, at least30 psig, or from about 20 to about 100 psig.

Aspect 48. The system of any one of aspects 45-47, wherein the at leastone first reactor vessel and the at least one second reactor vessel,independently, comprise a coating/layer comprising any suitable metal orany metal disclosed herein (e.g., tin) that provides resistance tocarburization and metal dusting.

Aspect 49. The system of any one of aspects 45-48, wherein the at leastone first reactor vessel and the at least one second reactor vessel,independently, are configured for decreasing temperature from the (firstor second) reactor inlet to the (first or second) reactor outlet.

Aspect 50. The system of any one of aspects 45-49, wherein the at leastone first reactor vessel and the at least one second reactor vessel areradial flow reactors.

Aspect 51. The system of any one of aspects 45-50, wherein the at leastone first reactor vessel and the at least one second reactor vessel areconfigured for a catalytic conversion of a non-aromatic hydrocarbon toan aromatic hydrocarbon (e.g., benzene, toluene, or xylenes).

Aspect 52. The system of any one of aspects 45-51, wherein the firstcatalyst support and the second catalyst support, independently,comprise a zeolite.

Aspect 53. The system of any one of aspects 45-52, wherein the firstcatalyst support and the second catalyst support, independently,comprise an L-zeolite, a Y-zeolite, a mordenite, an omega zeolite,and/or a beta zeolite.

Aspect 54. The system of any one of aspects 45-53, wherein the firstcatalyst support and the second catalyst support, independently,comprise a potassium L-zeolite or a barium ion-exchanged L-zeolite.

Aspect 55. The system of any one of aspects 45-54, wherein the firstcatalyst support and the second catalyst support, independently,comprise a binder comprising alumina, silica, a mixed oxide thereof, ora mixture thereof.

Aspect 56. The system of any one of aspects 45-55, wherein the firstcatalyst support and the second catalyst support, independently,comprise a silica-bound KL-zeolite catalyst support.

Aspect 57. The system of any one of aspects 45-56, wherein the firsttransition metal and the second transition metal, independently,comprise a Group 7-11 transition metal, or a Group 8-11 transitionmetal.

Aspect 58. The system of any one of aspects 45-57, wherein the firsttransition metal and the second transition metal, independently,comprise platinum, rhenium, gold, or combinations thereof.

Aspect 59. The system of any one of aspects 45-58, wherein the firsttransition metal and the second transition metal comprise platinum.

Aspect 60. The system of any one of aspects 45-59, wherein the firstaromatization catalyst and the second aromatization catalyst,independently, comprise platinum on a bound L-zeolite catalyst support.

Aspect 61. The system of any one of aspects 45-60, wherein the firstaromatization catalyst and the second aromatization catalyst,independently, comprise platinum on a bound KL-zeolite catalyst support.

Aspect 62. The system of any one of aspects 45-61, wherein the firstaromatization catalyst and the second aromatization catalyst,independently, comprise platinum on a silica-bound KL-zeolite catalystsupport.

Aspect 63. The system of any one of aspects 45-62, wherein the firstaromatization catalyst and the second aromatization catalyst furthercomprise chlorine and fluorine.

Aspect 64. The system of any one of aspects 45-63, wherein the firstaromatization catalyst has a first surface area in any range disclosedherein (e.g., from about 85 m²/g to about 140 m²/g), and the secondaromatization catalyst has a second surface area in any range disclosedherein (e.g., from about 165 m²/g to about 240 m²/g).

Aspect 65. The system of any one of aspects 45-64, wherein the firstaromatization catalyst has a first micropore volume in any rangedisclosed herein (e.g., from about 0.015 cc/g to about 0.045 cc/g), andthe second aromatization catalyst has a second micropore volume in anyrange disclosed herein (e.g., from about 0.055 cc/g to about 0.09 cc/g).

Aspect 66. The system of any one of aspects 45-65, wherein the firstaromatization catalyst contains more carbon (e.g., from about 0.01 wt. %to about 0.6 wt. %) than that of the second aromatization catalyst.

Aspect 67. The system of any one of aspects 45-66, wherein the firstaromatization catalyst is further characterized by an amount of carbonin any range disclosed herein (e.g., from about 0.01 to about 1 wt. %),and the second aromatization catalyst is further characterized by anamount of carbon in any range disclosed herein (e.g., less than 0.01 wt.%, or no measurable amount).

Aspect 68. The system of any one of aspects 45-67, wherein the firstaromatization catalyst contains less nitrogen (ppmw) than that of thesecond aromatization catalyst.

Aspect 69. The system of any one of aspects 45-68, wherein the firstaromatization catalyst contains more iron (Fe, ppmw) and/or more sulfur(ppmw) than that of the second aromatization catalyst.

Aspect 70. The system of any one of aspects 45-69, wherein the firstaromatization catalyst has a lower platinum dispersion (%) than that ofthe second aromatization catalyst.

Aspect 71. The system of any one of aspects 45-70, wherein the firstaromatization catalyst is further characterized by a platinum dispersionin any range disclosed herein (e.g., from about 25% to about 65%, orfrom about 30% to about 50%), and the second aromatization catalyst isfurther characterized by a platinum dispersion in any range disclosedherein (e.g., from about 60% to about 75%).

Aspect 72. The system of any one of aspects 45-71, wherein the firstaromatization catalyst has a lower catalyst activity than that of thesecond aromatization catalyst.

Aspect 73. The system of any one of aspects 45-72, wherein the firstaromatization catalyst has a catalyst selectivity that is substantiallythe same as or better than that of the second aromatization catalyst.

Aspect 74. The system of any one of aspects 45-73, wherein a weightratio of the first aromatization catalyst to the second aromatizationcatalyst in the reactor vessel system is in any range of first:seconddisclosed herein, e.g., from about 1:1.5 to about 1:30, from about 1:2to about 1:20, or from about 1:5 to about 1:15.

Aspect 75. The system of any one of aspects 45-74, wherein the systemcomprises a number of at least one first reactor vessels in any rangedisclosed herein (e.g., from 1 to 3 first reactor vessels in series),and the system comprises a number of at least one second reactor vesselsin any range disclosed herein (e.g., from 2 to 6 second reactor vesselsin series).

Aspect 76. The system of any one of aspects 45-75, wherein the systemcomprises any suitable number of total reactor vessels in series or anynumber of reactor vessels in series disclosed herein, e.g., from 2 to 8vessels in series, or 6 vessels in series.

Aspect 77. The system of any one of aspects 45-76, wherein the at leastone first reactor vessel and the at least one second reactor vessel,independently, are configured for a reforming temperature in anyreforming temperature range disclosed herein, e.g., from about 350° C.to about 600° C., or from about 400° C. to about 600° C.

Aspect 78. The system of any one of aspects 45-77, wherein the furnaceis configured to heat the first effluent to a reforming temperature ofthe at least one second reactor vessel of from about 350° C. to about600° C.

1. An aromatization process comprising: (i) introducing a firsthydrocarbon feed into at least one first reactor vessel comprising afirst aromatization catalyst, and contacting the first hydrocarbon feedwith the first aromatization catalyst under first reforming conditionsto produce a first aromatic product; wherein: the first aromatizationcatalyst comprises platinum and a first catalyst support, the firstaromatization catalyst characterized by: a first surface area in a rangefrom about 80 m²/g to about 150 m²/g; and/or a first micropore volume ina range from about 0.01 cc/g to about 0.048 cc/g; (ii) discharging afirst effluent comprising the first aromatic product from the at leastone first reactor vessel; (iii) heating the first effluent to form asecond hydrocarbon feed; (iv) introducing the second hydrocarbon feedinto at least one second reactor vessel comprising a secondaromatization catalyst, and contacting the second hydrocarbon feed withthe second aromatization catalyst under second reforming conditions toproduce a second aromatic product; wherein: the second aromatizationcatalyst comprises platinum and a second catalyst support, the secondaromatization catalyst characterized by: a second surface area in arange from about 160 m²/g to about 260 m²/g; and/or a second microporevolume in a range from about 0.05 cc/g to about 0.09 cc/g; and (v)discharging a second effluent comprising the second aromatic productfrom the at least one second reactor vessel, wherein: the firstaromatization catalyst is a regenerated catalyst; the firstaromatization catalyst has a lower platinum dispersion than that of thesecond aromatization catalyst and the first aromatization catalyst hasan aromatics selectivity that is substantially the same as or betterthan that of the second aromatization catalyst.
 2. The process of claim1, wherein: the first surface area is in a range from about 85 m²/g toabout 140 m²/g; the first micropore volume is in a range from about0.015 cc/g to about 0.045 cc/g; the second surface area is in a rangefrom about 165 m²/g to about 240 m²/g; and the second micropore volumeis in a range from about 0.05 cc/g to about 0.085 cc/g.
 3. The processof claim 1, wherein a weight ratio of the first aromatization catalystto the second aromatization catalyst is in a range from about 1:2 toabout 1:20.
 4. The process of claim 1, wherein the first aromatizationcatalyst contains more carbon, more sulfur, and/or more iron than thatof the second aromatization catalyst.
 5. The process of claim 1, whereinthe first aromatization catalyst has from 10% to 30% lower platinumdispersion than that of the second aromatization catalyst.
 6. Theprocess of claim 1, wherein: the first aromatization catalyst ischaracterized by a platinum dispersion in a range from about 30% toabout 50%; and the second aromatization catalyst is characterized by aplatinum dispersion in a range from about 60% to about 75%.
 7. Theprocess of claim 1, wherein: the at least one first reactor vesselcomprises from 1 to 3 first reactor vessels in series; and the at leastone second reactor vessel comprises from 2 to 6 second reactor vesselsin series.
 8. The process of claim 1, wherein: the first aromatizationcatalyst has a lower catalyst activity than that of the secondaromatization catalyst; and/or the first aromatization catalyst has abenzene+toluene selectivity that is substantially the same as or betterthan that of the second aromatization catalyst.
 9. The process of claim1, wherein: the first aromatization catalyst comprises from about 0.3wt. % to about 5 wt. % of platinum; and the second aromatizationcatalyst comprises from about 0.3 wt. % to about 5 wt. % of platinum.10. The process of claim 1, wherein: the first catalyst support and thesecond catalyst support comprise a KL-zeolite and a binder comprisingalumina, silica, a mixed oxide thereof, or a mixture thereof; and thefirst aromatization catalyst and the second aromatization catalystfurther comprise chlorine and fluorine.
 11. The process of claim 1,wherein: the first aromatic product and the second aromatic product,independently, comprise benzene, toluene, or a combination thereof; andthe first reforming conditions and the second reforming conditions,independently, comprise a reforming temperature in a range from about350° C. to about 600° C. 12-20. (canceled)
 21. The process of claim 1,wherein the at least one first reactor vessel and the at least onesecond reactor vessel are radial flow reactors.
 22. The process of claim1, wherein a weight ratio of the first aromatization catalyst to thesecond aromatization catalyst is in a range from about 1:5 to about1:15.
 23. The process of claim 10, wherein the first aromatizationcatalyst and the second aromatization catalyst, independently, comprisefrom about 0.3 wt. % to about 5 wt. % of platinum.
 24. The process ofclaim 23, wherein: the first surface area is in a range from about 85m²/g to about 140 m²/g; the first micropore volume is in a range fromabout 0.02 cc/g to about 0.04 cc/g; the second surface area is in arange from about 160 m²/g to about 220 m²/g; and the second microporevolume is in a range from about 0.055 cc/g to about 0.09 cc/g. 25 Theprocess of claim 23, wherein: a weight ratio of the first aromatizationcatalyst to the second aromatization catalyst is in a range from about1:2 to about 1:20; the first aromatization catalyst has from 10% to 30%lower platinum dispersion than that of the second aromatizationcatalyst; and the first aromatic product and the second aromaticproduct, independently, comprise benzene, toluene, or a combinationthereof.
 26. The process of claim 23, wherein: the first aromatizationcatalyst is characterized by a platinum dispersion in a range from about30% to about 50%; and the second aromatization catalyst is characterizedby a platinum dispersion in a range from about 60% to about 75%.
 27. Theprocess of claim 23, wherein: the first aromatization catalyst has alower catalyst activity than that of the second aromatization catalyst;and the first aromatization catalyst has a benzene +toluene selectivitythat is substantially the same as or better than that of the secondaromatization catalyst.